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m Reverting possible vandalism by DJ Autagirl to version by Rezonansowy. False positive? Report it. Thanks, ClueBot NG. (1693827) (Bot)
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{{about|the Internet encyclopedia}}
{{Selfref|For Wikipedia's non-encyclopedic visitor introduction, see {{srlink|Wikipedia:About}}. For the main page, see {{srlink|Main Page}}.}}
{{pp-semi|demolevel=semi|small=yes}}{{pp-move-indef}}
{{Use mdy dates|date=November 2012}}
{{Infobox website
| name = Wikipedia
| logo = [[File:Wikipedia-v2-logo.svg|frameless|150px|alt=A white sphere made of large jigsaw pieces. Letters from several alphabets are shown on the pieces.]] <br />[[File:Wikipedia wordmark.svg|150px|Wikipedia wordmark]]
| logocaption = The [[logo of Wikipedia]], a globe featuring [[glyph]]s from several writing systems
| screenshot = [[File:Www.wikipedia.org screenshot.png|border|300px|alt=Wikipedia's homepage with links to many languages.]]
| collapsible = yes
| caption = Screenshot of Wikipedia's multilingual portal
| url = {{URL|http://www.wikipedia.org|Wikipedia.org}}
| slogan = The Free Encyclopedia that anyone can edit
| commercial = No
| type = [[Internet encyclopedia]]
| registration = Optional, but is required for certain tasks such as editing protected pages, creating pages in English Wikipedia and uploading files
| language = 276 active editions (286 in total)
| num_users = Over 77,000 active editors<ref>{{cite web|url=http://stats.wikimedia.org/EN/TablesWikipediansEditsGt5.htm |title=Wikipedia Statistics - Tables - Active wikipedians |publisher=Stats.wikimedia.org |date= |accessdate=2013-07-04}}</ref>
| content license = {{nobr|[[Creative Commons licenses|CC Attribution / Share-Alike]] 3.0}}<br /><small>Most text also dual-licensed under [[GFDL]], media licensing varies</small>
| owner = [[Wikimedia Foundation]]
| author = [[Jimmy Wales]], [[Larry Sanger]]<ref name="Sidener" />
| launch date = {{Start date and years ago|mf=yes|2001|1|15}}
| alexa = {{down}} 7 ({{as of|2013|7|7|alt=July 2013}})<ref name="AlexaStats"/><!--Updated monthly by OKBot.-->
| current status = Active
}}


==See also==
'''Wikipedia''' ({{IPAc-en|audio=En-uk-Wikipedia.ogg|ˌ|w|ɪ|k|ɨ|ˈ|p|iː|d|i|ə}} or {{IPAc-en|audio=en-us-Wikipedia.ogg|ˌ|w|ɪ|k|i|ˈ|p|iː|d|i|ə}} {{respell|WIK|i|PEE|dee-ə}}) is a [[collaborative editing|collaboratively edited]], [[multilingualism|multilingual]], [[Free content|free]] [[Internet encyclopedia]] supported by the non-profit [[Wikimedia Foundation]]. Wikipedia's 30 million articles in 286 languages, including {{srlink|Wikipedia:Size of Wikipedia|over {{#expr:0.1*floor ({{NUMBEROFARTICLES:R}}/100000)}} million}} in the [[English Wikipedia]], are written collaboratively by [[Community of Wikipedia|volunteers]] around the world. Almost all of its articles can be edited by anyone having access to the site.<ref name="anyone" /> It is the largest and most popular general [[reference work]] on the [[Internet]],<ref name="AlexaStats" /><ref name="Tancer" /><ref name="Woodson" /><ref name="AlexaTop500" /><ref>{{cite web|url=http://www.comscore.com/Insights/Press_Releases/2012/9/comScore_Media_Metrix_Ranks_Top_50_US_Web_Properties_for_August_201|title=comScore MMX Ranks Top 50 U.S. Web Properties for August 2012|publisher=comScore|date=12 September 2012|accessdate=6 February 2013}}</ref> ranking seventh globally among all websites on [[Alexa Internet|Alexa]] as of July 2013, and having an estimated 365 million readers worldwide.<ref name="AlexaStats" /><ref name="365M" />
*[[WP:About]]

Wikipedia was launched on January 15, 2001, by [[Jimmy Wales]] and [[Larry Sanger]].<ref name="MiliardWho" /> Sanger coined the name ''[[wikt:Wikipedia|Wikipedia]]'',<ref>''How I started Wikipedia''. Presentation by Larry Sanger.</ref> which is a [[portmanteau]] of '''''[[wiki]]''''' (a type of collaborative website, from the [[Hawaiian language|Hawaiian]] word ''[[Wikt:wiki#Hawaiian|wiki]]'', meaning "quick")<ref>"Wiki" in the Hawaiian Dictionary, revised and enlarged edition, University of Hawaii Press, 1986</ref> and [[encyclopedia|''encyclo'''pedia''''']].

Wikipedia's departure from the expert-driven style of encyclopedia building and the presence of a large body of unacademic content have received extensive attention in print media. In 2006, ''Time'' magazine recognized Wikipedia's participation in the rapid growth of online collaboration and interaction by millions of people around the world, in addition to [[YouTube]], [[MySpace]], and [[Facebook]].<ref name="Time2006" /> Wikipedia has also been praised as a news source due to articles related to breaking news often being rapidly updated.<ref name="Dee" /><ref name="Lih" /><ref>{{cite web|url=http://www.wired.com/playbook/2012/08/how-wikipedia-won-olympic-gold/ |title=How Wikipedia Won Olympic Gold |author=Mossop, Brian |work=[[Wired (magazine)|Wired]] |date=August 10, 2012 |accessdate=2012-07-05}}</ref>

The open nature of Wikipedia has led to various concerns, such as the quality of writing,<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:About |title=Wikipedia:About – Wikipedia, the free encyclopedia |publisher=English Wikipedia |accessdate=2012-07-05}}</ref> the amount of [[Vandalism on Wikipedia|vandalism]]<ref name="MIT_IBM_study" /><ref name="CreatingDestroyingAndRestoringValue" /> and the accuracy of information. Some articles contain unverified or inconsistent information,<ref name="DeathByWikipedia" /> though a 2005 investigation in ''[[Nature (journal)|Nature]]'' showed that the science articles they compared came close to the level of accuracy of ''[[Encyclopædia Britannica]]'' and had a similar rate of "serious errors".<ref name="GilesJ2005Internet" /> ''Britannica'' replied that the study's methodology and conclusions were flawed,<ref name="corporate.britannica.com" /> but ''Nature'' reacted to this refutation with both a formal response and a point-by-point rebuttal of ''Britannica'''s main objections.<ref name="nature.com">{{cite web|work=Nature |url=http://www.nature.com/nature/britannica/index.html |title=Nature's responses to Encyclopaedia Britannica |date=March 30, 2006 |accessdate=2012-03-19}}</ref>

{{TOC limit|3}}

== Nature ==
{{rquote|right|As the popular joke goes, ‘The problem with Wikipedia is that it only works in practice. In theory, it can never work.’|Miikka Ryökäs|4={{clarify|date=June 2013}} <ref>{{cite news|last=Cohen |first=Noam |url=http://www.nytimes.com/2007/04/23/technology/23link.html?ex=1178510400&en=c0eb1b23e5c579f7&ei=5070 |title=The Latest on Virginia Tech, From Wikipedia |work=The New York Times |date=April 23, 2007 |accessdate=December 27, 2011}}</ref>}}

=== Editing ===
[[File:Wiki feel stupid v2.ogv|thumb|thumbtime=2|In April 2009, the [[Wikimedia Foundation]] conducted a Wikipedia usability study, questioning users about the editing mechanism.<ref>{{cite web|url=http://usability.wikimedia.org/wiki/UX_and_Usability_Study |title=UX and Usability Study |publisher=usability.wikimedia.org |accessdate=July 13, 2010}}</ref>]]

In a departure from the style of traditional encyclopedias, Wikipedia is open to outside editing. This means that, with the exception of particularly sensitive and/or vandalism-prone pages that are "protected" to some degree,<ref>{{srlink|Wikipedia:Protection Policy|Protection Policy}}</ref> the reader of an article can edit the text without needing approval, doing so with a registered account or even anonymously. Different language editions modify this policy to some extent; for example, only registered users may create a new article in the English edition.<ref>{{srlink|Wikipedia:Registration|Registration notes}}</ref> No article is considered to be owned by its creator or any other editor, nor is it vetted by any recognized authority. Instead, editors are supposed to agree on the content and structure of articles by {{srlink|WP:CONSENSUS|consensus}}.<ref>{{srlink|Wikipedia:Ownership of articles|Ownership of articles}}</ref>

By default, an edit to an article becomes available immediately, prior to any review. As such, an article may contain inaccuracies, ideological biases, or even patent nonsense, until or unless another editor corrects the problem. Different language editions, each under separate administrative control, are free to modify this policy. For example, the [[German Wikipedia]] maintains "stable versions" of articles,<ref>{{cite mailing list|first=P. |last=Birken |url=http://lists.wikimedia.org/pipermail/wikide-l/2008-December/021594.html |title=Bericht Gesichtete Versionen |mailinglist=Wikide-l |date=December 14, 2008 |language=German |publisher=Wikimedia Foundation |accessdate=February 15, 2009}}</ref> which have passed certain reviews. Following the protracted trials and community discussion, the "pending changes" system was introduced to English Wikipedia in December 2012.<ref>[http://www.businessinsider.com/pending-changes-safeguard-on-wikipedia-2012-12 ''Business Insider''].</ref> Under this system, new users' edits to certain controversial or vandalism-prone articles would be "subject to review from an established Wikipedia editor before publication".

[[File:History Comparison Example (Vector).png|thumb|left|alt=Web page showing side-by-side comparison of an article highlighting changed paragraphs.|Editors keep track of changes to articles by checking the difference between two revisions of a page, displayed here in yellow and blue.]]

Contributors, whether registered or not, can take advantage of features available in the software that powers Wikipedia. The "History" page belonging to each article records every single past revision of the article, though a revision with libelous content, criminal threats or copyright infringements may be removed retroactively.<ref name="Torsten_Kleinz" /> Editors can use this page to undo undesirable changes or restore lost content. The "Talk" page associated with each article helps coordinate work among multiple editors.<ref>{{cite journal|url=http://www.research.ibm.com/visual/papers/wikipedia_coordination_final.pdf|format=PDF|author=[[Fernanda B. Viégas]], [[Martin M. Wattenberg]], Jesse Kriss, Frank van Ham|title=Talk Before You Type: Coordination in Wikipedia|publisher=Visual Communication Lab, [[IBM Research]]|date=January 3, 2007|accessdate=June 27, 2008}}</ref> Importantly, editors may use the "Talk" page to reach consensus,<ref>Wikipedia:Consensus</ref> sometimes through the use of [[Voting|polling]].

In addition, editors may view the most [[Help:Recent changes|"recent changes"]] to the website, which are displayed in reverse chronology. Regular contributors often maintain a [[Watchlist (wiki)|"watchlist"]] of articles of interest to them, in order to easily track recent changes to those articles. In language editions with many articles, editors tend to prefer the "watchlist" because the number of edits has become too large to follow in "recent changes". New page patrol is a process by which newly created articles are checked for obvious problems.<ref>Wikipedia:New pages patrol</ref> A frequently vandalized article can be ''[[Wikipedia:Protection policy|semi-protected]]'', allowing only well established users to edit it.<ref>[[Protection policy#Semi-protection|English Wikipedia's semi-protection policy]]</ref> A particularly contentious article may be locked so that only administrators are able to make changes.<ref>{{srlink|Wikipedia:Full protection|English Wikipedia's full protection policy}}</ref>

[[File:Wikipedia editing interface.png|thumb|The editing interface of Wikipedia.]]

Computer programs called [[Internet bot|bots]] have been used widely to correct common misspellings and stylistic issues, or to start articles such as geography entries in a standard format from statistical data.<ref>{{srlink|Wikipedia:Bots|Wikipedia Bot Information}}</ref><ref>{{cite news |title=Meet the 'bots' that edit Wikipedia |url=http://www.bbc.co.uk/news/magazine-18892510 |author=Daniel Nasaw |publisher=BBC News |date=July 24, 2012}}</ref><ref name="guardianblog halliday 2012">{{cite news|last=Halliday|first=Josh|author2=Arthur, Charles|title=Boot up: The Wikipedia vandalism police, Apple analysts, and more|url=http://www.guardian.co.uk/technology/blog/2012/jul/26/boot-up-wikipedia-apple|newspaper=[[The Guardian]]|date=July 26, 2012|accessdate=September 5, 2012}}</ref> There are also some bots designed to warn users making "undesirable" edits,<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:Wikipedia_Signpost/2009-03-23/Abuse_Filter |title=Wikipedia signpost: Abuse Filter is enabled |publisher=English Wikipedia |date=March 23, 2009 |accessdate=July 13, 2010}}</ref> block on the creation of links to particular websites, and block on edits from particular accounts or [[IP address]] ranges. Bots on Wikipedia must be approved by administration prior to activation.<ref>{{srlink|Wikipedia:Bot Policy|Bot Policy}}</ref>

=== Organization of article pages ===
Articles in Wikipedia are loosely organized according to their {{srlink|Wikipedia:Version 1.0 Editorial Team/Assessment|development status}} and {{srlink|Wikipedia:Categorization|subject matter}}.<ref>Wikipedia:Categorization</ref> A new article often starts as a [[Wikipedia:Stub|"stub"]], a very short page consisting of definitions and some links. On the other extreme, the most developed articles may be nominated for [[Wikipedia:Featured article criteria|"featured article"]] status. One "featured article" per day, as selected by editors, appears on the [[main page]] of Wikipedia.<ref>{{cite web|url=http://firstmonday.org/htbin/cgiwrap/bin/ojs/index.php/fm/article/view/2365/2182 |title=Comparing featured article groups and revision patterns correlations in Wikipedia|publisher=[[First Monday (journal)|First Monday]] |accessdate=July 13, 2010}}</ref><ref>{{cite journal|url=http://www.research.ibm.com/visual/papers/hidden_order_wikipedia.pdf|author=Fernanda B. Viégas, Martin Wattenberg, and Matthew M. McKeon|title=The Hidden Order of Wikipedia|publisher=Visual Communication Lab, IBM Research
|date=July 22, 2007|format=PDF|accessdate=October 30, 2007}}</ref> Researcher Giacomo Poderi found that articles tend to reach featured status via the intensive work of a few editors.<ref>Poderi, Giacomo, ''Wikipedia and the Featured Articles: How a Technological System Can Produce Best Quality Articles'', Master thesis, [[University of Maastricht]], October 2008.</ref> A 2010 study found unevenness in quality among featured articles and concluded that the community process is ineffective in assessing the quality of articles.<ref>{{cite news |url=http://firstmonday.org/htbin/cgiwrap/bin/ojs/index.php/fm/article/viewArticle/2721/2482 |title=Evaluating quality control of Wikipedia's featured articles. |author=David Lindsey |publisher=First Monday}}</ref> In 2007, in preparation for producing a print version, the [[English-language Wikipedia]] introduced an assessment scale against which the quality of articles is judged.<ref>{{cite web
|url=https://en.wikipedia.org/wiki/Wikipedia:Version_1.0_Editorial_Team/Assessment|title=Wikipedia:Version 1.0 Editorial Team/Assessment|accessdate=October 28, 2007}}</ref>

A group of Wikipedia editors may form a [[Wikipedia:WikiProject|WikiProject]] to focus their work on a specific topic area, using its associated discussion page to coordinate changes across multiple articles. <!-- Might need to be expanded. -->

=== Vandalism ===
{{main|Vandalism on Wikipedia}}

Any edit that changes content in a way that deliberately compromises the integrity of Wikipedia is considered vandalism. The most common and obvious types of vandalism include insertion of obscenities and crude humor. Vandalism can also include advertising language, and other types of [[Wikipedia:Spam|spam]].<ref>[http://repository.upenn.edu/cgi/viewcontent.cgi?article=1508&context=cis_papers Link spamming Wikipedia for profit] (2011)</ref> Sometimes editors commit vandalism by removing information or entirely blanking a given page. Less common types of vandalism, such as the deliberate addition of plausible but false information to an article, can be more difficult to detect. Vandals can introduce irrelevant formatting, modify page semantics such as the page's title or categorization, manipulate the underlying code of an article, or utilize images disruptively.<ref>{{cite web|title=Vandalism|url=http://en.wikipedia.org/wiki/Wikipedia:Vandalism|publisher=Wikipedia|accessdate=November 6, 2012}}</ref>

The opportunity for vandalism provides a number of unique challenges to Wikipedia. One criticism is that, at any moment, a reader of an article cannot be certain that it has not been compromised by the insertion of false information or the removal of essential information. Former ''Encyclopædia Britannica'' editor-in-chief [[Robert McHenry]] once described the predicament using a simile: <ref>{{cite web|url=http://www.caslon.com.au/wikiprofile1.htm |title=Caslon Analytics: wiki and wikipedia|publisher=Caslon Analytics|accessdate=July 13, 2010}}</ref> <ref>{{cite web
|url=http://www.tcsdaily.com/article.aspx?id=111504A
|title= The Faith-Based Encyclopedia
|publisher=[[TCS Daily]]
|author=Robert McHenry
|date=November 15, 2004
|accessdate=September 10, 2009}}</ref>

{{quote|The user who visits Wikipedia to learn about some subject, to confirm some matter of fact, is rather in the position of a visitor to a public restroom. It may be obviously dirty, so that he knows to exercise great care, or it may seem fairly clean, so that he may be lulled into a false sense of security. What he certainly does not know is who has used the facilities before him.}}

[[File:John Seigenthaler Sr. speaking.jpg|thumb|left|alt=White-haired elderly gentleman in suit and tie speaks at a podium.|[[John Seigenthaler]] has described Wikipedia as "a flawed and irresponsible research tool".<ref name="Seigenthaler" />]]

Obvious vandalism is generally easy to remove from wiki articles; in practice, the median time to detect and fix vandalism is a few minutes.<ref name="MIT_IBM_study" /><ref name="CreatingDestroyingAndRestoringValue" /> However, in [[Wikipedia biography controversy|one high-profile incident in 2005]], false information was introduced into the biography of American political figure [[John Seigenthaler]] and remained undetected for four months.<ref name="Seigenthaler" /> John Seigenthaler, the founding editorial director of ''[[USA Today]]'' and founder of the [[Freedom Forum]] [[First Amendment Center]] at [[Vanderbilt University]], called Wales and asked whether he had any way of knowing who contributed the misinformation. Wales replied that he did not, although the perpetrator was eventually traced.<ref>{{cite book|last=Friedman|first=Thomas L.|title=The World is Flat|year=2007|publisher=[[Farrar, Straus & Giroux]]|isbn=978-0-374-29278-2|page=124}}</ref><ref>{{cite web|url=http://archive.firstamendmentcenter.org/news.aspx?id=17798 |title=Founder shares cautionary tale of libel in cyberspace | first=Brian J. |last=Buchanan |publisher=archive.firstamendmentcenter.org |date=November 17, 2006 |accessdate=November 17, 2012}}</ref> This incident led to policy changes on the site, specifically targeted at tightening up the verifiability of all {{srlink|WP:BLP|biographical articles of living people}}.<ref>{{cite news|last=Helm|first=Burt|title=Wikipedia: "A Work in Progress"|url=http://www.businessweek.com/stories/2005-12-13/wikipedia-a-work-in-progress|newspaper=[[Business Week]]|date=December 13, 2005|accessdate=July 26, 2012}}</ref>

=== Rules and laws governing content and editor behavior ===
Content in Wikipedia is subject to the laws (in particular, the [[copyright|copyright laws]]) of the [[USA|United States]] and of the [[U.S. State|U.S. state]] of [[Florida]], where the majority of Wikipedia's servers are located. Beyond legal matters, the editorial principles of Wikipedia are embodied in the {{srlink|WP:Five pillars|"five pillars"}}, and numerous {{srlink|Wikipedia:List of policies and guidelines|policies and guidelines}} that are intended to shape the content appropriately. Even these rules are stored in wiki form, and Wikipedia editors as a community write and revise the website's policies and guidelines.<ref>{{cite web|url=http://www.pcworld.idg.com.au/index.php/id;1866322157;fp;2;fpid;2 |title=Who's behind Wikipedia?|work=PC World |date=February 6, 2008 |accessdate=February 7, 2008}}</ref> Editors can enforce rules by deleting or modifying non-compliant material. Originally, rules on the non-English editions of Wikipedia were based on a translation of the rules on the English Wikipedia. They have since diverged to some extent.
{{clear}}

==== English Wikipedia ====
{{main|English Wikipedia}}

[[File:Wikipedia Main Page.png|thumb|Main Page of the English Wikipedia on October 20, 2010.]]
[[File:Wikipedia mobile version on iPodToch's Safari.png|thumb|The mobile version of the English Wikipedia [[Main Page]] in the [[Safari web browser]] on an [[iPod Touch]]]]

===== Content policies =====
According to the rules on the English Wikipedia, each entry in Wikipedia, to be worthy of inclusion, must be about a topic that is [[wikt:encyclopedic|encyclopedic]] and is not a [[dictionary]] entry or dictionary-like.<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:ISNOT |title=Wikipedia:ISNOT |quote=Wikipedia is not a dictionary, usage, or jargon guide.|accessdate=April 1, 2010 }}</ref> A topic should also meet Wikipedia's standards of [[Notability in Wikipedia|"notability"]],<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:Notability |title=Wikipedia:Notability |quote=A topic is presumed to be notable if it has received significant coverage in reliable secondary sources that are independent of the subject.|accessdate=February 13, 2008 }}</ref> which usually means that it must have received significant coverage in reliable secondary sources such as mainstream media or major academic journals that are independent of the subject of the topic. Further, Wikipedia intends to convey only knowledge that is already established and recognized.<ref name="NOR" /> It must not present new information or original research. A claim that is likely to be challenged requires a reference to a reliable source. Among Wikipedia editors, this is often phrased as "verifiability, not truth" to express the idea that the readers, not the encyclopedia, are ultimately responsible for checking the truthfulness of the articles and making their own interpretations.<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:Verifiability |title= Wikipedia:Verifiability |quote=Material challenged or likely to be challenged, and all quotations, must be attributed to a reliable, published source.|accessdate=February 13, 2008 }}</ref> This can lead to the removal of information that is valid, thus hindering inclusion of knowledge and growth of the encyclopedia.<ref>{{cite news | last = Cohen | first = Noam | title = For inclusive mission, Wikipedia is told that written word goes only so far | newspaper = [[International Herald Tribune]] | page = 18 | date = August 9, 2011 | url = | quote =In the case of [[dabba kali]], a children's game played in the Indian state of [[Kerala]] there was a Wikipedia article in the local language, [[Malayalam]], that included photos, a drawing, and a detailed description of the rules. but no sources to back up what was written. Other than, of course the 40 million people who played it as children. There is no doubt...that the article would have been deleted from English Wikipedia if it not had any sources to cite. Those are the rules of the game. | postscript = {{inconsistent citations}}}}</ref> Finally, Wikipedia must not take sides.<ref name="autogenerated2" /> All opinions and viewpoints, if attributable to external sources, must enjoy an appropriate share of coverage within an article.<ref>{{cite web|url=http://www.alternet.org/story/61365/?page=entire|title=Will Unethical Editing Destroy Wikipedia's Credibility?|author=Eric Haas|publisher=AlterNet|date=October 26, 2007|accessdate=December 26, 2008}}</ref> This is known as neutral point of view ([[WP:NPOV|NPOV]]).

===== Dispute resolution =====
Wikipedia has many methods of settling disputes. A [[Wikipedia:BOLD, revert, discuss cycle|"BOLD, revert, discuss" cycle]] sometimes occurs, in which an editor changes something, another editor reverts the change, and then the two editors discuss the issue on a talk page. When editors disregard this process – when a change is repeatedly done by one editor and then undone by another – an [[Wikipedia:Edit warring|"edit war"]] may be asserted to have begun.<ref>{{srlink|Wikipedia:Dispute Resolution|Dispute Resolution}}</ref> The provenance of this phrase "edit war" is unknown.<ref>{{cite web | url=http://www.nbcnews.com/technology/technolog/wikipedia-editorial-warzone-says-study-838793 | title=Wikipedia is editorial warzone, says study | author=Coldewey, Devin|publisher=[[NBC News]] | work=Technology | date=June 21, 2012 | accessdate=October 29, 2012 }}</ref>

In order to gain a broader community consensus, editors can raise issues at the [[Wikipedia:Village pump|Village Pump]], or initiate a [[Wikipedia:Request for comment|Request for Comment]]. An editor can report impolite, uncivil, or otherwise problematic communications with another editor via the [[Wikipedia:Wikiquette assistance|"Wikiquette Assistance"]] noticeboard. {{Update-small|date=September 2012}} Such postings themselves have no binding or disciplinary power. Specialized forums exist for centralizing discussion on specific decisions, such as whether or not an article should be deleted. [[Mediation]] is sometimes used, although it has been deemed by some Wikipedians to be unhelpful for resolving particularly contentious disputes.<ref>{{srlink|Wikipedia:Mediation|Mediation on Wikipedia}}</ref>

===== Arbitration =====
The [[Wikipedia Arbitration Committee|Arbitration Committee]] is the ultimate dispute resolution method. Although disputes usually arise from a disagreement between two opposing views on how articles should read, the Arbitration Committee explicitly refuses to directly rule on which view should be adopted. Statistical analyses suggest that the committee ignores the content of disputes and focuses on the way disputes are conducted instead,<ref>{{cite journal|title=Wikitruth through Wikiorder|url=http://www.law.emory.edu/fileadmin/journals/elj/59/59.1/Hoffman_Mehra.pdf|publisher=Emory Law Journal|volume=59|issue=1|year=2009|page=181|author=Hoffman, David A., Mehra, Salil K.}}</ref> functioning not so much to resolve disputes and make peace between conflicting editors, but to weed out problematic editors while allowing potentially productive editors back in to participate. Therefore, the committee does not dictate the <!-- The committee may (directly) rule that a content change is inappropriate, but may NOT (directly) rule that a certain content is inappropriate. -->content of articles, although it sometimes condemns content changes when it deems the new content violates Wikipedia policies (for example, if the new content is [[Wikipedia:Neutral point of view|biased]]). Its remedies include cautions and [[probation]]s (used in 63.2% of cases) and banning editors from articles (43.3%), subject matters (23.4%) or Wikipedia (15.7%). Complete bans from Wikipedia are largely limited to instances of impersonation and [[anti-social behavior]]. When conduct is not impersonation or anti-social, but rather anti-consensus<!-- This needs to be clarified. Anti-consensus behavior appears to be defined mostly as "edit warring". --> or violating editing policies, warnings tend to be issued.<ref>{{cite journal|title=Wikitruth through Wikiorder|url=http://www.law.emory.edu/fileadmin/journals/elj/59/59.1/Hoffman_Mehra.pdf|publisher=[[Emory Law Journal]]|volume=59|issue=1|year=2009|pages=151–210|author=Hoffman, David A., Mehra, Salil K.|postscript=}}</ref>

=== Privacy ===
One [[privacy]] concern in the case of Wikipedia is the right of a private citizen to remain private: to remain a "private citizen" rather than a "[[public figure]]" in the eyes of the law.<ref>See [http://texaspress.com/index.php/publications/law-media/731-law-a-the-media-in-texas--libel-cases "Libel"] by David McHam for the legal distinction</ref> It is a battle between the right to be anonymous in [[cyberspace]] and the right to be anonymous in [[real life]] ("[[meatspace]]"). A particular problem occurs in the case of an individual who is relatively unimportant and for whom there exists a Wikipedia page against her or his wishes.

In January 2006, a German court ordered the [[German Wikipedia]] shut down within Germany because it stated the full name of [[Tron (hacker)|Boris Floricic]], aka "Tron", a deceased hacker. On February 9, 2006, the injunction against Wikimedia Deutschland was overturned, with the court rejecting the notion that Tron's right to privacy or that of his parents were being violated.<ref>[http://www.heise.de/newsticker/meldung/Gericht-weist-einstweilige-Verfuegung-gegen-Wikimedia-Deutschland-ab-Update-173587.html Heise – {{lang|de|Gericht weist einstweilige Verfügung gegen Wikimedia Deutschland ab}} <nowiki>[Update]</nowiki>], by Torsten Kleinz, February 9, 2006.</ref>

=== Community ===
{{main|Community of Wikipedia}}

[[File:WIkimania-2006 010.jpg|thumb|[[Wikimania]], an annual conference for users of Wikipedia and other projects operated by the Wikimedia Foundation.]]

Wikipedia's community has been described as [[cult|cult-like]],<ref>{{cite news
|url=http://www.guardian.co.uk/technology/2005/dec/15/wikipedia.web20
|title=Log on and join in, but beware the web cults
|first=Charles |last=Arthur
|date=December 15, 2005
|work=[[The Guardian]] |location=London |accessdate=December 26, 2008 }}</ref> although not always with entirely negative connotations,<ref>{{cite news
|url=http://www.cnn.com/2003/TECH/internet/08/03/wikipedia/index.html
|title=Wikipedia: The know-it-all Web site
|first=Kristie
|last=Lu Stout
|publisher=CNN
|date=August 4, 2003
|accessdate=December 26, 2008}}</ref> and criticized for failing to accommodate inexperienced users.<ref>{{cite web
|url=http://wikinfo.org/index.php/Critical_views_of_Wikipedia
|title=Critical views of Wikipedia
|author=Wikinfo
|date=March 30, 2005
|accessdate=January 29, 2007
}} {{broken link|date=June 2013}}</ref><!-- While they are welcomed by the community,<ref name="TheNewYorker">
{{cite news
|first=Stacy
|last=Schiff
|title=Can Wikipedia conquer expertise?
|work=The New Yorker
|url=http://www.newyorker.com/archive/2006/07/31/060731fa_fact
|date=July 24, 2006
|accessdate=March 25, 2007}}</ref> authors new to Wikipedia are encouraged to read policies to help them learn the ways of Wikipedia.<ref name="Torsten_Kleinz" /> --><nowiki> </nowiki>The project's preference for cohesiveness, even if it requires compromise that includes disregard of [[credential]]s, has been referred to as "[[anti-elitism]]".<ref>{{cite web|title=Why Wikipedia Must Jettison Its Anti-Elitism|url=http://www.kuro5hin.org/story/2004/12/30/142458/25|work=[[Kuro5hin.org|Kuro5hin]], Op–Ed|author=[[Larry Sanger]]|date=December 31, 2004|quote=There is a certain mindset associated with unmoderated Usenet groups […] that infects the collectively-managed Wikipedia project: if you react strongly to trolling, that reflects poorly on you, not (necessarily) on the troll. If you […] demand that something be done about constant disruption by trollish behavior, the other listmembers will cry "censorship," attack you, and even come to the defense of the troll. […] The root problem: anti-elitism, or lack of respect for expertise. There is a deeper problem […] which explains both of the above-elaborated problems. Namely, as a community, Wikipedia lacks the habit or tradition of respect for expertise. As a community, far from being elitist, it is anti-elitist (which, in this context, means that expertise is not accorded any special respect, and snubs and disrespect of expertise is tolerated). This is one of my failures: a policy that I attempted to institute in Wikipedia's first year, but for which I did not muster adequate support, was the policy of respecting and deferring politely to experts. (Those who were there will, I hope, remember that I tried very hard.)}}</ref>

==== Power structure ====
The Wikipedia community has established "a bureaucracy of sorts", including "a clear power structure that gives volunteer administrators the authority to exercise editorial control".<ref name="NYTimesJune17-2006" /><ref name="iTWireJune18-2006" /><ref>{{cite news|url=http://www.slate.com/id/2184487 |title=The Wisdom of the Chaperones |date=February 22, 2008 |first=Chris |last=Wilson |work=[[Slate (magazine)|Slate]] |accessdate=March 4, 2008}}</ref>

Editors in good standing in the community can run for one of many levels of volunteer stewardship: this begins with "administrator",<ref>{{srlink|Wikipedia:Administrators}}</ref><ref name="David_Mehegan" /> a group of privileged users who have the ability to delete pages, lock articles from being changed in case of vandalism or editorial disputes, and block users from editing. Despite the name, administrators are not supposed to enjoy any special privilege in decision-making; instead, their powers are mostly limited to making edits that have project-wide effects and thus are disallowed to ordinary editors, and to block users making disruptive edits (such as vandalism).<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:Administrators#Administrator_conduct |title=Wikipedia:Administrators |accessdate=July 12, 2009}}</ref><ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:RfA_Review/Reflect |title=Wikipedia:RfA_Review/Reflect |accessdate=September 24, 2009}}</ref><!-- From the beginning, the role of founder Jimmy Wales, within the Wikipedia community, has been unclear, while co-founder Larry Sanger in the early days had served as an editor-in-chief. --> As the process of vetting potential Wikipedia administrators has become more rigorous, fewer editors are promoted to admin status than in years past.<ref>{{cite web |url=http://www.theatlantic.com/technology/archive/2012/07/3-charts-that-show-how-wikipedia-is-running-out-of-admins/259829/ |title=3 Charts That Show How Wikipedia Is Running Out of Admins |last=Meyer |first=Robinson |work=[[The Atlantic]] |date=July 16, 2012 |accessdate=September 2, 2012}}</ref>

==== Contributors ====
[[File:WMFstratplanSurvey1.png|thumb|left|Demographics of Wikipedia editors.]]

Wikipedia does not require that its users provide identification.<ref name="user identification" /> However, as Wikipedia grew, "Who writes Wikipedia?" became one of the questions frequently asked on the project, often with a reference to other Web 2.0 projects such as [[Digg]].<ref>{{cite web|url=http://www.viktoria.se/altchi/submissions/submission_edchi_1.pdf |title=Power of the Few vs. Wisdom of the Crowd: Wikipedia and the Rise of the Bourgeoisie | publisher= [[Viktoria Institute]]|first=Aniket |last=Kittur |format=PDF | accessdate=February 23, 2008}}</ref> Wales once argued that only "a community&nbsp;... a dedicated group of a few hundred volunteers" makes the bulk of contributions to Wikipedia and that the project is therefore "much like any traditional organization". Wales performed a study finding that over 50% of all the edits were done by just 0.7% of the users (at the time: 524 people). This method of evaluating contributions was later disputed by [[Aaron Swartz]], who noted that several articles he sampled had large portions of their content (measured by number of characters) contributed by users with low edit counts.<ref>{{cite web|url=http://www.aaronsw.com/weblog/whowriteswikipedia |title=Raw Thought: Who Writes Wikipedia? |first=Aaron |last=Swartz |date=September 4, 2006 |accessdate=February 23, 2008}}</ref> A 2007 study by researchers from [[Dartmouth College]] found that "anonymous and infrequent contributors to Wikipedia ... are as reliable a source of knowledge as those contributors who register with the site".<ref>{{cite news |url=http://www.sciam.com/article.cfm?id=good-samaritans-are-on-the-money |title=Wikipedia "Good Samaritans" Are on the Money |work=Scientific American |date=October 19, 2007 |accessdate=December 26, 2008}}</ref>

In 2003, economics PhD student Andrea Ciffolilli argued that the low [[transaction cost]]s of participating in [[wiki]] software create a catalyst for collaborative development, and that such features as easy access to past versions of a page favor "creative construction" over "creative destruction".<ref>Andrea Ciffolilli, [http://firstmonday.org/article/view/1108/1028 "Phantom authority, self-selective recruitment and retention of members in virtual communities: The case of Wikipedia"], ''[[First Monday (journal)|First Monday]]'' December 2003.</ref> In his 2008 book, ''[[The Future Of The Internet|The Future of the Internet and How to Stop It]]'', Zittrain cites Wikipedia's success as a case study in how open collaboration has fostered innovation on the web.<ref>{{cite book |last=Zittrain |first=Jonathan |title=The Future of the Internet and How to Stop It&nbsp;– Chapter 6: The Lessons of Wikipedia |author-link=Jonathan Zittrain |publisher=Yale University Press |year=2008 |url=http://yupnet.org/zittrain/archives/16 |isbn=978-0-300-12487-3 |accessdate=December 26, 2008}}</ref> A 2008 study found that Wikipedians were less agreeable, open, and conscientious than others.<ref>Yair Amichai–Hamburger, Naama Lamdan, Rinat Madiel, Tsahi Hayat, [http://www.liebertonline.com/doi/abs/10.1089/cpb.2007.0225 Personality Characteristics of Wikipedia Members], ''CyberPsychology & Behavior'', December 1, 2008, 11 (6): 679–681; {{doi|10.1089/cpb.2007.0225}}.</ref><ref>{{cite web|url=http://www.newscientist.com/article/mg20126883.900-wikipedians-are-closed-and-disagreeable.html |title=Wikipedians are 'closed' and 'disagreeable' |work=New Scientist |accessdate=July 13, 2010}} {{subscription required|s}}</ref> A 2009 study suggested there was "evidence of growing resistance from the Wikipedia community to new content".<ref>{{cite web|last=Giles|first=Jim|title=After the boom, is Wikipedia heading for bust?|url=http://www.newscientist.com/article/dn17554-after-the-boom-is-wikipedia-heading-for-bust.html|work=New Scientist|date=August 4, 2009}}</ref>

At [[OOPSLA]] 2009, [[Wikimedia]] [[chief technology officer]] and senior [[software]] architect Brion Vibber gave a presentation entitled "Community Performance Optimization: Making Your People Run as Smoothly as Your Site"<ref>{{cite web|url=http://www.infoq.com/presentations/vibber-community-perf-opt |title=InfoQ |publisher=InfoQ |accessdate=July 13, 2010}}</ref> in which he discussed the challenges of handling the contributions from a large community and compared the process to that of software development.

==== Interactions ====
[[File:Editing Hoxne Hoard at the British Museum.ogv|thumb|Wikipedians and [[British Museum]] curators collaborate on the article [[Hoxne Hoard]] in June 2010.]]

Members of the community interact with each other predominantly via "talk" pages, which are wiki-edited pages that are associated with articles, as well as via talk pages that are specific to particular contributors, and talk pages that help run the site. These pages help the contributors reach consensus about what the contents of the articles should be, how the site's rules may change, and to take actions with respect to any problems within the community.<ref>[[Help:Using talk pages]] – "A talk page (also known as a discussion page) is a page which editors can use to discuss improvements to an article or other Wikipedia page." Retrieved April 18, 2011.</ref>

''The Wikipedia Signpost'' is the community newspaper on the [[English Wikipedia]],<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:Wikipedia_Signpost|title=''The Wikipedia Signpost''|publisher=Wikipedia|accessdate=March 24, 2009}}</ref> and was founded by [[Michael Snow (attorney)|Michael Snow]], an administrator and the former chair of the [[Wikimedia Foundation]] board of trustees.<ref>{{cite news|url=http://www.nytimes.com/2007/03/05/technology/05wikipedia.html?pagewanted=2&_r=1 |title=A Contributor to Wikipedia Has His Fictional Side |first=Noam |last=Cohen |work=The New York Times |date=March 5, 2007 |accessdate=October 18, 2008}}</ref> It covers news and events from the site, as well as major events from sister projects, such as [[Wikimedia Commons]].<ref>{{cite news|url=http://www.webpronews.com/blogtalk/2005/12/19/ten-more-wikipedia-hacks |title=Ten More Wikipedia Hacks |first=Steve |last=Rubel |work=WebProNews|date=December 19, 2005 |accessdate=October 18, 2008}}</ref>

==== Positive reinforcement ====
Wikipedians sometimes award one another [[barnstar]]s for good work. These personalized tokens of appreciation reveal a wide range of valued work extending far beyond simple editing to include social support, administrative actions, and types of articulation work. The barnstar phenomenon has been analyzed by researchers seeking to determine what implications it might have for other communities engaged in large-scale collaborations.<ref>{{cite journal|title=Articulations of wikiwork: uncovering valued work in Wikipedia through barnstars|author=T. Kriplean|author-separator=,|author2=I. Beschastnikh|display-authors=2|last3=McDonald|first3=David W.|url=http://portal.acm.org/citation.cfm?id=1460563.1460573|publisher=Proceedings of the ACM|year=2008|doi=10.1145/1460563.1460573|page=47|chapter=Articulations of wikiwork|isbn=978-1-60558-007-4|postscript=}}</ref>

==== New users ====
Up to sixty percent of Wikipedia's registered users never make another edit after their first 24 hours. Possible explanations are that such users register for only a single purpose, or are scared away by their experiences.<ref>{{cite journal|title=Wikipedians Are Born, Not Made|author=Panciera, Katherine|display-authors=1|author2=<!-- Please add first missing authors to populate metadata. -->|publisher=Association for Computing Machinery, Proceedings of the ACM Conference on Supporting Group Work|pages=51, 59|year=2009|postscript=}}</ref> Goldman writes that editors who fail to comply with Wikipedia cultural rituals, such as signing talk pages, implicitly signal that they are Wikipedia outsiders, increasing the odds that Wikipedia insiders will target their contributions as a threat. Becoming a Wikipedia insider involves non-trivial costs: the contributor is expected to build a user page, learn Wikipedia-specific technological codes, submit to an arcane dispute resolution process, and learn a "baffling culture rich with in-jokes and insider references". Non-logged-in users are in some sense second-class citizens on Wikipedia,<ref>{{cite journal|title=Wikipedia's Labor Squeeze and its Consequences|publisher=Journal on Telecommunications and High Technology Law|author=Goldman, Eric|volume=8|postscript=}}</ref> as "participants are accredited by members of the wiki community, who have a vested interest in preserving the quality of the work product, on the basis of their ongoing participation",<ref>{{cite journal|title=Wikipedia and the Future of Legal Education|author=Noveck, Beth Simone|publisher=Journal of Legal Education|volume=57|postscript=}}</ref> but the contribution histories of [[IP addresses]] cannot necessarily with any certainty be credited to, or blamed upon, a particular user.

A 2009 study by [[Business Insider]] editor and journalist [[Henry Blodget]]<ref>{{cite web | url=http://www.businessinsider.com/2009/1/who-the-hell-writes-wikipedia-anyway | title=Who The Hell Writes Wikipedia, Anyway? | work=Business Insider | date=January 3, 2009 | accessdate=July 23, 2011 | author=Blodget, Henry}}</ref> showed that in a random sample of articles most content in Wikipedia (measured by the amount of contributed text that survives to the latest sampled edit) is created by "outsiders" (users with low edit counts), while most editing and formatting is done by "insiders" (a select group of established users).

==== Demographics ====
[[File:User demography.tif|thumb|Estimation of contributions shares from different regions in the world to different Wikipedia editions.]]

One study found that the contributor base to Wikipedia "was barely 13% women; the average age of a contributor was in the mid-20s". [[Sue Gardner]], executive director of the Wikimedia Foundation, hopes to see female editing contributions increase to twenty-five percent by 2015.<ref>{{cite news|last=Chom|first=Noam|title=Define Gender Gap? Look Up Wikipedia's Contributor List |url=http://www.nytimes.com/2011/01/31/business/media/31link.html?scp=1&sq=wikipedia%20gender&st=cse|newspaper=The New York Times|date=January 31, 2011|page=B–1|accessdate=May 9, 2012}}</ref> Linda Basch, president of the National Council for Research on Women, noted the contrast in these Wikipedia editor statistics with the percentage of women currently completing bachelor's degrees, master's degrees and PhD programs in the [[USA|United States]] (all at rates of fifty percent or greater).<ref>{{cite news|last=Basch|first=Linda|title=Male-Dominated Web Site Seeking Female Experts|url=http://www.nytimes.com/2011/02/06/opinion/l06wiki.html|accessdate=May 9, 2012|newspaper=The New York Times|date=February 6, 2011|page=WK–7|format=Letters to the Editor}}</ref>

In a research article published in [[PLoS ONE]] in 2012, Yasseri et al., based on the circadian patterns of editorial activities of the community, have estimated the share of contributions to different editions of Wikipedia from different regions of the world. For instance, it has been reported that edits from [[North America]] are limited to almost 50% in the [[English Wikipedia]] and this value decreases to twenty-five percent in [[simple English Wikipedia]]. The article also covers some other editions in different languages.<ref>{{cite web | url=http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0030091 | title=Circadian Patterns of Wikipedia Editorial Activity: A Demographic Analysis | date=January 17, 2012 | publisher= [[PLoS ONE]] |author=Taha Yasseri, Robert Sumi, [[János Kertész]]| accessdate=January 17, 2012 }}</ref> The Wikimedia Foundation hopes to increase the number of editors in the Global South to thirty-seven percent by 2015.<ref>{{cite web|title=Wikimedia Foundation 2011–12 Annual Plan|url=http://upload.wikimedia.org/wikipedia/foundation/3/37/2011-12_Wikimedia_Foundation_Plan_FINAL_FOR_WEBSITE_.pdf|publisher=Wikimedia Foundation|page=8}}</ref>

=== Language editions ===
{{see also|List of Wikipedias}}

[[File:PercentWikipediasGraph.png|thumb|300px|Percentage of all Wikipedia articles in English (red) and top ten largest language editions (blue). As of July 2007 less than 23% of Wikipedia articles are in English.]]

There are currently 285 [[List of Wikipedias|language editions (or language versions) of Wikipedia]]; of these, seven have over one million articles each ([[English Wikipedia|English]], [[German Wikipedia|German]], [[Dutch Wikipedia|Dutch]], [[French Wikipedia|French]], [[Italian Wikipedia|Italian]], [[Spanish Wikipedia|Spanish]] and [[Russian Wikipedia|Russian]]), four more have over 700,000 articles ([[Swedish Wikipedia|Swedish]], [[Polish Wikipedia|Polish]], [[Japanese Wikipedia|Japanese]] and [[Portuguese Wikipedia|Portuguese]]), 35 more have over 100,000 articles and 73 more have over 10,000&nbsp;articles.<ref name="ListOfWikipedias" /> <ref>[[meta:List of Wikipedias|List of Wikipedias]]</ref> The largest, the English Wikipedia, has over {{#expr: 0.1*floor({{NUMBEROFARTICLES:R}}/100000)}} million articles. {{as of|2013|06}}, according to Alexa, the English [[subdomain]] (en.wikipedia.org; [[English Wikipedia]]) receives approximately 56% of Wikipedia's cumulative traffic, with the remaining split among the other languages (Spanish: 9%; Japanese: 8%; Russian: 6%; German: 5%; French: 4%; Italian: 3%).<ref name="AlexaStats" /> As of April 2013, the five largest language editions are (in order of article count) the [[English Wikipedia|English]], [[German Wikipedia|German]], [[Dutch Wikipedia|Dutch]], [[French Wikipedia|French]], and [[Italian Wikipedia]]s.<ref>{{cite web|url=http://meta.wikimedia.org/wiki/List_of_Wikipedias#All_Wikipedias_ordered_by_number_of_articles
|title=Wikipedia:List of Wikipedias |publisher=English Wikipedia |accessdate=April 4, 2013}}</ref> The coexistence of multilingual content on Wikipedia is made possible by [[Unicode]], whose support was first introduced into Wikipedia in January 2002 by [[Brion Vibber]] after he had similarly implemented [[Esperanto orthography|the alphabet]] of [[Esperanto]].<ref>{{cite web|url=http://en.wikipedia.org/wiki/Wikipedia:Wikipedia_Signpost/2012-12-31/Interview|title= Interview with Brion Vibber, the WMF's first employee | work = The Signpost | publisher = Wikipedia |accessdate=January 14, 2013}}</ref><ref>{{cite web |url=http://blogs.transparent.com/esperanto/unicoding-the-esperanto-wikipedia/ |title=Unicoding the Esperanto Wikipedia (Part 3 of 4) |work=Esperanto Language Blog |author=Chuck Smith |accessdate=January 14, 2013}}</ref>

Since Wikipedia is based on the [[World Wide Web|Web]] and therefore worldwide, contributors of a same language edition may use different dialects or may come from different countries (as is the case for the [[English Wikipedia|English edition]]). These differences may lead to some conflicts over [[American and British English spelling differences|spelling differences]] (e.g. ''colour'' versus ''color'')<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:Spelling|title= Spelling | work = Manual of Style | publisher = Wikipedia |accessdate=May 19, 2007}}</ref> or points of view.<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:WikiProject_Countering_systemic_bias|title=Countering systemic bias|accessdate=May 19, 2007}}</ref>

Though the various language editions are held to global policies such as "neutral point of view", they diverge on some points of policy and practice, most notably on whether images that are not [[free content|licensed freely]] may be used under a claim of [[fair use]].<ref>{{cite web
|url=http://meta.wikimedia.org/wiki/Fair_use
|title=Fair use
|publisher=Meta-Wiki
|accessdate=July 14, 2007}}</ref><ref>{{cite web
|url=http://meta.wikimedia.org/wiki/Images_on_Wikipedia
|title=Images on Wikipedia
|accessdate=July 14, 2007}}</ref><ref>{{cite journal
|url=http://www.research.ibm.com/visual/papers/viegas_hicss_visual_wikipedia.pdf
|format=PDF|author=Fernanda B. Viégas
|title=The Visual Side of Wikipedia
|publisher=Visual Communication Lab, IBM Research
|date=January 3, 2007
|accessdate=October 30, 2007}}</ref>

Jimmy Wales has described Wikipedia as "an effort to create and distribute a free encyclopedia of the highest possible quality to every single person on the planet in their own language".<ref>[[Jimmy Wales]], [http://lists.wikimedia.org/pipermail/wikipedia-l/2005-March/020469.html "Wikipedia is an encyclopedia"], March 8, 2005, &lt;Wikipedia-l@wikimedia.org&gt;</ref> Though each language edition functions more or less independently, some efforts are made to supervise them all. They are coordinated in part by Meta-Wiki, the Wikimedia Foundation's wiki devoted to maintaining all of its projects (Wikipedia and others).<ref>{{cite web|url=http://meta.wikimedia.org|title=Meta-Wiki|publisher=Wikimedia Foundation|accessdate=March 24, 2009}}</ref> For instance, Meta-Wiki provides important statistics on all language editions of Wikipedia,<ref>{{cite web|url=http://meta.wikimedia.org/wiki/Statistics|title=Meta-Wiki Statistics|publisher=Wikimedia Foundation|accessdate=March 24, 2008}}</ref> and it maintains a list of articles every Wikipedia should have.<ref>{{cite web|url=http://meta.wikimedia.org/wiki/List_of_articles_every_Wikipedia_should_have|title=List of articles every Wikipedia should have|publisher=Wikimedia Foundation|accessdate=March 24, 2008}}</ref> The list concerns basic content by subject: biography, history, geography, society, culture, science, technology, and mathematics. As for the rest, it is not rare for articles strongly related to a particular language not to have counterparts in another edition. For example, articles about small towns in the United States might only be available in English, even when they meet notability criteria of other language Wikipedia projects.

Translated articles represent only a small portion of articles in most editions, in part because fully automated translation of articles is disallowed.<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:Translations |title=Wikipedia: Translation |work=English Wikipedia |accessdate=February 3, 2007}}</ref> Articles available in more than one language may offer "[[interwiki links]]", which link to the counterpart articles in other editions.

== History ==
{{main|History of Wikipedia}}

[[File:Nupedia logo and wordmark.png|thumb|alt=Logo reading "Nupedia.com the free encyclopedia" in blue with large initial "N".|Wikipedia originally developed from another encyclopedia project, [[Nupedia]].]]

Wikipedia began as a complementary project for [[Nupedia]], a free online [[English language|English-language]] encyclopedia project whose articles were written by experts and reviewed under a formal process. Nupedia was founded on March 9, 2000, under the ownership of [[Bomis]], a [[web portal]] company. Its main figures were the Bomis {{abbr|CEO|chief executive officer}} Jimmy Wales and [[Larry Sanger]], [[Editing|editor-in-chief]] for Nupedia and later Wikipedia. Nupedia was licensed initially under its own Nupedia [[Open Content]] License, switching to the [[GNU Free Documentation License]] before Wikipedia's founding at the urging of [[Richard Stallman]].<ref name="stallman1999" /> Sanger and Wales founded Wikipedia.<ref name="autogenerated1" /><ref name="Meyers" /> While Wales is credited with defining the goal of making a publicly editable encyclopedia,<ref name="SangerMemoir" /><ref name="Sanger" /> Sanger is usually credited with the strategy of using a [[wiki]] to reach that goal.<ref>{{cite web|url=http://lists.wikimedia.org/pipermail/wikipedia-l/2001-October/000671.html|title=Wikipedia-l: LinkBacks?|accessdate=February 20, 2007}}</ref> On January 10, 2001, Sanger proposed on the Nupedia [[electronic mailing list|mailing list]] to create a wiki as a "feeder" project for Nupedia.<ref>{{cite news|first=Larry |last=Sanger|title=Let's Make a Wiki|date=January 10, 2001|publisher=Internet Archive|url=http://www.nupedia.com/pipermail/nupedia-l/2001-January/000676.html|archiveurl=http://web.archive.org/web/20030414014355/http://www.nupedia.com/pipermail/nupedia-l/2001-January/000676.html|archivedate=April 14, 2003 |accessdate=December 26, 2008}}</ref>

Wikipedia was formally launched on January 15, 2001, as a single English-language edition at www.wikipedia.com,<ref name="WikipediaHome" /> and announced by Sanger on the Nupedia mailing list.<ref name="SangerMemoir" /> Wikipedia's policy of "neutral point-of-view"<ref name="NPOV" /> was codified in its initial months. Otherwise, there were relatively few rules initially and Wikipedia operated independently of Nupedia.<ref name="SangerMemoir" />

[[File:EnwikipediaGom.PNG|thumb|right|Number of articles in the English Wikipedia (in blue)]]

Wikipedia gained early contributors from Nupedia, [[Slashdot]] postings, and [[web search engine]] indexing. On August 8, 2001, Wikipedia had over 8,000 articles.<ref name="Wikipedia August 08, 2001">[http://web.archive.bibalex.org/web/20010808121638/http://www.wikipedia.org/ Wikipedia, August 8, 2001]</ref> On September 25, 2001, Wikipedia had over 13,000 articles.<ref name="Wikipedia September 25, 2001">[http://web.archive.bibalex.org/web/20011010233257/www.wikipedia.com/ Wikipedia, September 25, 2001]</ref> And by the end of 2001 it had grown to approximately 20,000 articles and 18 language editions. By late 2002, it had reached 26 language editions, 46 by the end of 2003, and 161 by the final days of 2004.<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:Multilingual_statistics |title=Multilingual statistics |work=Wikipedia |date=March 30, 2005 |accessdate=December 26, 2008}}</ref> Nupedia and Wikipedia coexisted until the former's servers were taken down permanently in 2003, and its text was incorporated into Wikipedia. [[English Wikipedia]] passed the mark of two million articles on September 9, 2007, making it the largest encyclopedia ever assembled, surpassing even the 1407 [[Yongle Encyclopedia]], which had held the record for 600&nbsp;years.<ref name="EB_encyclopedia" />

Citing fears of commercial advertising and lack of control in Wikipedia, users of the [[Spanish Wikipedia]] [[Fork (software development)|forked]] from Wikipedia to create the ''[[Enciclopedia Libre Universal en Español|Enciclopedia Libre]]'' in February 2002.<ref>{{cite web|title=<nowiki>[long] Enciclopedia Libre: msg#00008</nowiki>|url=http://osdir.com/ml/science.linguistics.wikipedia.international/2003-03/msg00008.html |work=Osdir |accessdate=December 26, 2008}}</ref> These moves encouraged Wales to announce that Wikipedia would not display advertisements, and to change Wikipedia's domain from ''wikipedia.com'' to ''wikipedia.org''.<ref name="Shirky" />

[[File:EnwikipediagrowthGom.PNG|thumb|right|Growth of the number of articles in the English Wikipedia (in blue)]]

Though the English Wikipedia reached three million articles in August 2009, the growth of the edition, in terms of the numbers of articles and of contributors, appears to have peaked around early 2007.<ref>{{cite news|url=http://www.guardian.co.uk/technology/2009/aug/12/wikipedia-deletionist-inclusionist |title=Wikipedia approaches its limits |author=Bobbie Johnson |work=The Guardian |location=London | date=August 12, 2009 | accessdate=March 31, 2010}}</ref> Around 1,800 articles were added daily to the encyclopedia in 2006; by 2013 that average was roughly 800.<ref>{{srlink|Wikipedia:Modelling_Wikipedia_extended_growth}}</ref> A team at the [[Palo Alto Research Center]] attributed this slowing of growth to the project's increasing exclusivity and resistance to change.<ref>{{cite conference |url=http://www.wikisym.org/ws2009/procfiles/p108-suh.pdf |title=The Singularity is Not Near: Slowing Growth of Wikipedia |year=2009|location=Orlando, Florida |conference=The International Symposium on Wikis}}</ref> <!-- ''Hidden whilst in discussion on the talk page'': New or occasional editors have significantly higher rates of their edits reverted (removed) than an elite group of regular editors, colloquially known as "the [[cabal]]". This could make it more difficult for the project to recruit and retain new contributors over the long term, resulting in stagnation in article creation. --> Others suggest that the growth is flattening naturally because articles that could be called [[wikt:low-hanging fruit|"low-hanging fruit"]] – topics that clearly merit an article – have already been created and built up extensively.<ref>{{cite news|url=http://www.bostonreview.net/BR34.6/morozov.php |title=Edit This Page; Is it the end of Wikipedia |publisher=Boston Review |author=Evgeny Morozov|date=November/December 2009}}</ref><ref>{{cite news|last=Cohen |first=Noam |url=http://www.nytimes.com/2009/03/29/weekinreview/29cohen.html |title=Wikipedia – Exploring Fact City |work=The New York Times |date=March 28, 2009 |accessdate=April 19, 2011}}</ref><ref>Austin Gibbons, David Vetrano, Susan Biancani (2012). [http://www.stanford.edu/class/cs341/reports/09-GibbonsVetranoBiancaniCS341.pdf Wikipedia: Nowhere to grow] {{open access}}</ref>

In November 2009, a researcher at the [[Rey Juan Carlos University]] in [[Madrid]] ([[Spain]]) found that the English Wikipedia had lost 49,000 editors during the first three months of 2009; in comparison, the project lost only 4,900 editors during the same period in 2008.<ref>{{cite news|url=http://www.guardian.co.uk/technology/2009/nov/26/wikipedia-losing-disgruntled-editors |title=Wikipedia falling victim to a war of words |work=The Guardian |location=London |author=Jenny Kleeman | date=November 26, 2009 | accessdate=March 31, 2010}}</ref><ref>{{cite journal|url=http://libresoft.es/publications/thesis-jfelipe |title=Wikipedia: A quantitative analysis |format=PDF}}</ref> ''The Wall Street Journal'' cited the array of rules applied to editing and disputes related to such content among the reasons for this trend.<ref>Volunteers Log Off as Wikipedia Ages, The Wall Street Journal, November 27, 2009.</ref> Wales disputed these claims in 2009, denying the decline and questioning the methodology of the study.<ref>{{cite news|url=http://www.telegraph.co.uk/technology/wikipedia/6660646/Wikipedias-Jimmy-Wales-denies-site-is-losing-thousands-of-volunteer-editors.html |title=Wikipedia's Jimmy Wales denies site is 'losing' thousands of volunteer editors | first=Emma | last=Barnett|work=The Daily Telegraph | location=London | date=November 26, 2009 | accessdate=March 31, 2010 }}</ref> Two years later, Wales acknowledged the presence of a slight decline, noting a decrease from "a little more than 36,000 writers" in June 2010 to 35,800 in June 2011.<ref name="wiki-women" /> Nevertheless, in the same interview, he claimed the number of editors was "stable and sustainable". In July 2012, ''[[the Atlantic]]'' reported that the number of administrators is also in decline.<ref>{{cite news|url=http://www.theatlantic.com/technology/archive/2012/07/3-charts-that-show-how-wikipedia-is-running-out-of-admins/259829 |title=3 Charts That Show How Wikipedia Is Running Out of Admins |work=The Atlantic|date=July 16, 2012 }}</ref>

In January 2007, Wikipedia entered for the first time the top-ten list of the most popular websites in the United States, according to comScore Networks. With 42.9 million unique visitors, Wikipedia was ranked number 9, surpassing the ''[[New York Times]]'' (#10) and [[Apple Inc.|Apple]] (#11). This marked a significant increase over January 2006, when the rank was number 33, with Wikipedia receiving around 18.3 million unique visitors.<ref>{{cite web|url=http://www.pcworld.com/article/129135/wikipedia_breaks_into_us_top_10_sites.html |title=Wikipedia Breaks Into U.S. Top 10 Sites |publisher=PCWorld |date=February 17, 2007}}</ref> {{As of|2013|06}}, Wikipedia is the seventh most popular website worldwide according to [[Alexa Internet]],<ref name="AlexaStats" /> receiving more than 2.7 billion U.S. pageviews every month,<ref name="TCrunch" /> out of a global monthly total of over 12 billion pageviews.<ref>http://stats.wikimedia.org/wikimedia/squids/SquidReportPageViewsPerCountryOverview.htm [[Wikimedia]] Statistics. April 20, 2011. Retrieved October 14, 2011.</ref>

[[File:History Wikipedia English SOPA 2012 Blackout2.jpg|thumb|right|Wikipedia blackout protest against [[Stop Online Piracy Act|SOPA]] on January 18, 2012]]

On January 18, 2012, the English Wikipedia participated in a series of coordinated protests against two proposed laws in the United States Congress—the [[Stop Online Piracy Act]] (SOPA) and the [[PROTECT IP Act]] (PIPA)—by [[2012 Wikipedia blackout|blacking out its pages for 24 hours]].<ref name="LA Times Jan 19">{{cite news | url = http://latimesblogs.latimes.com/technology/2012/01/wikipedia-sopa-blackout-congressional-representatives.html | title = Wikipedia: SOPA protest led 8 million to look up reps in Congress | first = Deborah | last = Netburn |work = Los Angeles Times | date = January 19, 2012 | accessdate = 2012-03-06 }}</ref> More than 162 million people viewed the blackout explanation page that temporarily replaced Wikipedia content.<ref>{{cite news |title=Wikipedia joins blackout protest at US anti-piracy moves |url=http://www.bbc.co.uk/news/technology-16590585 |publisher=BBC News |date=January 18, 2012 |accessdate=January 19, 2012}}</ref><ref>{{cite web |url=http://wikimediafoundation.org/wiki/SOPA/Blackoutpage |title=SOPA/Blackoutpage |publisher=Wikimedia Foundation |accessdate=January 19, 2012}}</ref>

Loveland and Reagle argue that, in process, Wikipedia follows a long tradition of historical encyclopedias that accumulated improvements piecemeal through "[[Stigmergy|stigmergic]] accumulation".<ref>{{cite journal | url=http://nms.sagepub.com/content/early/2013/01/13/1461444812470428.full |title=Wikipedia and encyclopedic production. New Media & Society. Sage Journals|author=Jeff Loveland and Joseph Reagle|date=January 15, 2013 | journal=New Media & Society| doi=10.1177/1461444812470428}}</ref><ref>{{cite web|url=http://www.theatlantic.com/technology/archive/2013/01/what-if-the-great-wikipedia-revolution-was-actually-a-reversion/272697/|title=What If the Great Wikipedia 'Revolution' Was Actually a Reversion? • The Atlantic|author=Rebecca J. Rosen|date=Jan 30, 2013|accessdate=9 Feb, 2013}}</ref>

== Analysis of content ==
{{see also|Academic studies about Wikipedia|Criticism of Wikipedia}}

Although poorly written articles are flagged for improvement,<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:Contact_us/Article_problem/Poorly_written |title=Wikipedia:Contact us/Article problem/Poorly written – Wikipedia, the free encyclopedia |publisher=English Wikipedia |accessdate=2012-07-05}}</ref> critics note that the style and quality of individual articles may vary greatly. Others argue that inherent biases (willful or not) arise in the presentation of facts, especially controversial topics and public or historical figures. Although Wikipedia's stated mission is to provide information and not argue value judgements, articles often contain overly specialized, trivial, or objectionable material.<ref>{{cite web|url=https://www.ncjrs.gov/App/abstractdb/AbstractDBDetails.aspx?id=19162 |title=Abstracts Database – National Criminal Justice Reference Service |publisher=National Criminal Justice Reference Service, USA |accessdate=2012-07-05}}</ref>

In 2006, the ''Wikipedia Watch'' criticism website listed dozens of examples of [[plagiarism]] by Wikipedia editors on the English version.<ref name="wwplagiarism" /> Wales has said in this respect: "We need to deal with such activities with absolute harshness, no mercy, because this kind of plagiarism is 100% at odds with all of our core principles."<ref name="wwplagiarism" />

=== Accuracy of content ===
{{main|Reliability of Wikipedia}}

Articles for traditional encyclopedias such as ''[[Encyclopædia Britannica]]'' are carefully and deliberately written by experts, lending such encyclopedias a reputation for accuracy. Conversely, Wikipedia is often cited for factual inaccuracies and misrepresentations. However, a non-scientific report in the journal ''[[Nature (journal)|Nature]]'' in 2005 suggested that for some scientific articles Wikipedia came close to the level of accuracy of ''Encyclopædia Britannica'' and had a similar rate of "serious errors."<ref name="GilesJ2005Internet" /> These claims have been disputed by, among others, ''Encyclopædia Britannica''.<ref name="corporate.britannica.com" /><ref>{{cite web|url=http://www.nature.com/press_releases/Britannica_response.pdf?item|title=Encyclopaedia Britannica and Nature: a response|accessdate=July 13, 2010}}</ref> Although ''Nature'' gave a point by point rebuttal of ''Britannica's'' argument,<ref name="nature.com" /> the ''Nature'' report did agree that the structure of Wikipedia's articles was often poor.

As a consequence of the open structure, Wikipedia "makes no guarantee of validity" of its content, since no one is ultimately responsible for any claims appearing in it.<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:General_disclaimer |title=Wikipedia:General disclaimer |publisher=English Wikipedia |accessdate=April 22, 2008}}</ref> Concerns have been raised regarding the lack of [[accountability]] that results from users' anonymity,<ref name="WikipediaWatch" /> the insertion of false information,<ref>{{cite web|last=Raphel |first=JR|url=http://www.pcworld.com/article/170874/the_15_biggest_wikipedia_blunders.html|title=The 15 Biggest Wikipedia Blunders |work=[[PC World (magazine)|PC World]]|accessdate=September 2, 2009}}</ref> [[vandalism]], and similar problems.

Economist [[Tyler Cowen]] wrote: "If I had to guess whether Wikipedia or the median refereed journal article on economics was more likely to be true, after a not so long think I would opt for Wikipedia." He comments that some traditional sources of non-fiction suffer from systemic biases and novel results, in his opinion, are over-reported in journal articles and relevant information is omitted from news reports. However, he also cautions that errors are frequently found on Internet sites, and that academics and experts must be vigilant in correcting them.<ref>{{cite web|url=http://www.tnr.com/story.html?id=82eb5d70-13bd-4086-9ec0-cb0e9e8411b3
|archiveurl=http://web.archive.org/web/20080318103017/http://www.tnr.com/story.html?id=82eb5d70-13bd-4086-9ec0-cb0e9e8411b3|archivedate=March 18, 2008|title=Cooked Books|first=Tyler|last=Cowen|work=The New Republic
|date=March 14, 2008|accessdate=December 26, 2008}}</ref>

Critics argue that Wikipedia's open nature and a lack of proper sources for most of the information makes it unreliable.<ref>{{cite news|author=Stacy Schiff | date=July 31, 2006 |title = Know It All |work = The New Yorker}}</ref> Some commentators suggest that Wikipedia may be reliable, but that the reliability of any given article is not clear.<ref name="AcademiaAndWikipedia" /> Editors of traditional [[reference work]]s such as the ''Encyclopædia Britannica'' have questioned the project's [[utility]] and status as an encyclopedia.<ref name="McHenry_2004" />

Wikipedia's open structure inherently makes it an easy target for Internet [[troll (Internet)|trolls]], [[Spam (electronic)|spamming]], and those with an agenda to push.<ref name="Torsten_Kleinz" /><ref>{{cite web
|title=Toward a New Compendium of Knowledge (longer version)
|url=http://www.citizendium.org/essay.html
|work=Citizendium
|accessdate=October 10, 2006
}}</ref> The addition of political [[Spin (public relations)|spin]] to articles by organizations including members of the [[United States House of Representatives|US House of Representatives]] and special interest groups<ref name="DeathByWikipedia" /> has been noted,<ref>{{cite web
|url=http://news.cnet.com/8301-10784_3-6032713-7.html
|title=Politicians notice Wikipedia
|publisher=CNET
|author=Kane, Margaret
|date=January 30, 2006
|accessdate=January 28, 2007
}}</ref> and organizations such as [[Microsoft]] have offered financial incentives to work on certain articles.<ref>{{cite web
|url=http://www.msnbc.msn.com/id/16775981/
|title=Microsoft offers cash for Wikipedia edit
|publisher=MSNBC
|author=Bergstein, Brian
|authorlink=Brian Bergstein
|date=January 23, 2007
|accessdate=February 1, 2007
}}</ref> For example, in August 2007, the website [[WikiScanner]] began to trace the sources of changes made to Wikipedia by anonymous editors without Wikipedia accounts. The program revealed that many such edits were made by corporations or government agencies changing the content of articles related to them, their personnel or their work.<ref name="Seeing Corporate Fingerprints" /> These issues have been parodied, notably by [[Stephen Colbert]] on ''[[The Colbert Report]]''.<ref name="wikiality" />

=== Quality of writing ===
Because contributors usually rewrite small portions of an entry rather than making full-length revisions, high- and low-quality content may be intermingled within an entry. [[Roy Rosenzweig]], a history professor, stated that ''American National Biography Online'' outperformed Wikipedia in terms of its "clear and engaging prose", which, he said, was an important aspect of good historical writing.<ref name="Rosenzweig" /> Contrasting Wikipedia's treatment of [[Abraham Lincoln]] to that of [[American Civil War|Civil War]] historian [[James M. McPherson|James McPherson]] in ''American National Biography Online'', he said that both were essentially accurate and covered the major episodes in Lincoln's life, but praised "McPherson's richer contextualization... his artful use of quotations to capture Lincoln's voice ... and ... his ability to convey a profound message in a handful of words." By contrast, he gives an example of Wikipedia's prose that he finds "both verbose and dull". Rosenzweig also criticized the "waffling—encouraged by the npov policy—[which] means that it is hard to discern any overall interpretive stance in Wikipedia history". By example, he quoted the conclusion of Wikipedia's article on [[William Clarke Quantrill]]. While generally praising the article, he pointed out its "waffling" conclusion: "Some historians...remember him as an opportunistic, bloodthirsty outlaw, while others continue to view him as a daring soldier and local folk hero."<ref name="Rosenzweig" />

Other critics have made similar charges that, even if Wikipedia articles are factually accurate, they are often written in a poor, almost unreadable style. Frequent Wikipedia critic Andrew Orlowski commented: "Even when a Wikipedia entry is 100 per cent factually correct, and those facts have been carefully chosen, it all too often reads as if it has been translated from one language to another then into to a third, passing an illiterate translator at each stage."<ref>{{cite web|url=http://www.theregister.co.uk/2005/10/18/wikipedia_quality_problem/page2.html|title=Wikipedia founder admits to serious quality problems|author=Andrew Orlowski|work=The Register|date=October 18, 2005|accessdate=September 30, 2007}}</ref> A study of [[cancer]] articles by Yaacov Lawrence of the Kimmel Cancer Center at [[Thomas Jefferson University]] found that the entries were mostly accurate, but they were written at college reading level, as opposed to the ninth grade level seen in the [[Physician Data Query]]. He said that "Wikipedia's lack of readability may reflect its varied origins and haphazard editing".<ref>{{cite news|url=http://www.upi.com/Health_News/2010/06/04/Wikipedia-cancer-information-accurate/UPI-87311275628573/|title=Wikipedia cancer information accurate|work=UPI|date=June 4, 2010|accessdate=December 31, 2010}}</ref> ''The Economist'' argued that better-written articles tend to be more reliable: "inelegant or ranting prose usually reflects muddled thoughts and incomplete information".<ref>{{cite news|url=http://www.economist.com/node/8820422?story_id=8820422|title=Fact or fiction? Wikipedia's variety of contributors is not only a strength|work=The Economist|date=March 10, 2007|accessdate=December 31, 2010}}</ref>

=== Coverage of topics and systemic bias ===
{{see also|Notability in English Wikipedia}}

Wikipedia seeks to create a summary of all [[human]] knowledge in the form of an online encyclopedia, with each topic of knowledge covered encyclopedically in one article. Since it has [[terabyte]]s of disk space, it can have far more topics than can be covered by any conventional printed encyclopedia.<ref>{{srlink|Wikipedia:PAPER}}</ref> It also contains materials that some people may find objectionable, offensive, or pornographic (see further).<ref>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:Wikipedia_is_not#Wikipedia_is_not_censored |title=Wikipedia is not censored |publisher=Wikipedia |accessdate=April 30, 2008}}</ref> It was made clear that this policy is not up for debate, and the policy has sometimes proved controversial. For instance, in 2008, Wikipedia rejected an online petition against the inclusion of [[Online petition on Wikipedia Muhammad article|Muhammad's depictions]] in its [[English Wikipedia|English edition]], citing this policy. The presence of politically, religiously, and pornographically sensitive materials in Wikipedia has led to the [[censorship of Wikipedia]] by national authorities in [[China]],<ref name="Taylor" /> [[Pakistan]]<ref>{{cite news|url=http://www.washingtonpost.com/wp-dyn/content/article/2010/05/20/AR2010052005073.html|title=Pakistan blocks YouTube a day after shutdown of Facebook over Muhammad issue|first=Karin|last=Bruilliard|work=The Washington Post|date=May 21, 2010|accessdate=October 24, 2011}}</ref> and the [[United Kingdom]],<ref>{{cite news |title=Wikipedia child image censored |url= http://news.bbc.co.uk/1/hi/uk/7770456.stm|publisher=BBC News |date=December 8, 2008 |accessdate=December 8, 2008}}</ref> among other countries. In addition, Larry Sanger, co-founder of Wikipedia, has criticized Wikipedia not for the pornographic content but for the fact that the content is accessible to children, and contains extreme and detailed photographs and films.<ref name="autogenerated4">{{cite web|last=Sanger|first=Larry|title=What should we do about Wikipedia's porn problem?|url=http://larrysanger.org/2012/05/what-should-we-do-about-wikipedias-porn-problem/|accessdate=July 26, 2012}}</ref>

A 2008 study conducted by researchers at Carnegie Mellon University and Palo Alto Research Center gave a distribution of topics as well as growth (from July 2006 to January 2008) in each field:<ref name="Kittur2009" />

[[File:Wikipedia content by subject.png|thumb|Pie chart of Wikipedia content by subject as of January 2008<ref name=Kittur2009/>]]

{{refbegin|30em}}
* Culture and the arts: 30% (210%)
* Biographies and persons: 15% (97%)
* Geography and places: 14% (52%)
* Society and social sciences: 12% (83%)
* History and events: 11% (143%)
* Natural and physical sciences: 9% (213%)
* Technology and the applied sciences: 4% (−6%)
* Religions and belief systems: 2% (38%)
* Health: 2% (42%)
* Mathematics and logic: 1% (146%)
* Thought and philosophy: 1% (160%)
{{refend}}

These numbers refer only to the quantity of articles: it is possible for one topic to contain a large number of short articles and another to contain a small number of large ones. Through its "Wikipedia Loves Libraries" program, Wikipedia has partnered with major public libraries such as the New York Public Library for the Performing Arts to expand its coverage of underrepresented subjects and articles.<ref>{{cite news |url=http://www.nytimes.com/2011/10/21/theater/editing-wikipedia-at-the-new-york-public-library-for-the-performing-arts.html |title=Wikipedia's Deep Dive Into a Library Collection |last=Petrusich |first=Amanda |work=The New York Times |date=October 20, 2011 |accessdate=October 28, 2011}}</ref>

Furthermore, the exact coverage of Wikipedia is under constant review by the editors, and disagreements are not uncommon (see also [[deletionism and inclusionism in Wikipedia|deletionism and inclusionism]]).<ref>{{cite news|title=The battle for Wikipedia's soul |url=http://www.economist.com/printedition/displaystory.cfm?story_id=10789354 |work=The Economist|date=March 6, 2008 |accessdate=March 7, 2008 }}</ref><ref>{{cite news|title=Wikipedia: an online encyclopedia torn apart |first=Ian|last=Douglas|work=The Daily Telegraph |location=London |date=November 10, 2007|url=http://www.telegraph.co.uk/technology/3354752/Wikipedia-an-online-encyclopedia-torn-apart.html|accessdate=November 23, 2010}}</ref>

{{As of|2009|9}}, Wikipedia articles cover about half a million places on Earth. However, research conducted by the Oxford Internet Institute has shown that the geographic distribution of articles is highly uneven. Most articles are written about [[North America]], [[Europe]], and [[East Asia|East]] [[Asia]], with very little coverage of large parts of the developing world, including most of [[Africa]].<ref>{{cite web|url=http://zerogeography.blogspot.com/2009/11/mapping-geographies-of-wikipedia.html |title=Mapping the Geographies of Wikipedia Content |work=Mark Graham Oxford Internet Institute|publisher=ZeroGeography |accessdate=November 16, 2009}}</ref>

When multiple editors contribute to one topic or set of topics, there may arise a [[systemic bias]], such as non-opposite definitions for apparent antonyms. In 2011 Wales noted that the unevenness of coverage is a reflection of the demography of the editors, which predominantly consists of young males with high education levels in the developed world ({{lang|la|{{dabbr|cf|confer}}}} previously)<ref name="wiki-women">{{cite news |title=Wikipedia seeks women to balance its 'geeky' editors |author=Kevin Rawlinson |newspaper=The Independent |url=http://www.independent.co.uk/life-style/gadgets-and-tech/news/wikipedia-seeks-women-to-balance-its-geeky-editors-2333605.html |date=August 8, 2011|accessdate=April 5, 2012 }}</ref> Systemic bias on Wikipedia may follow that of culture generally, for example favouring certain ethnicities or majority religions.<ref name="Quilter">{{cite web | url=http://works.bepress.com/cgi/viewcontent.cgi?article=1035&context=laura_quilter | title=Systemic Bias in Wikipedia : What It Looks Like, and How to Deal with It | author=Quilter, Laura| publisher=University of Massachusetts – Amherst | date=24 October 2012 | accessdate=November 26, 2012 }}</ref> It may more specifically follow the biases of [[Internet]] culture, inclining to being young, male, English speaking, educated, technologically aware, and wealthy enough to spare time for editing. Biases of its own may include over-emphasis on topics such as pop culture, technology, and current events.<ref name="Quilter" />

A "selection bias"<ref>{{cite journal |title=Selection Bias, Demographic Effects, and Ability Effects in Common Value Auction Experiments |first=Marco |last=Casari |first2=John C. |last2=Ham |first3=John H. |last3=Kagel |journal=[[American Economic Review]] |volume=97 |issue=4 |year=2007 |pages=1278–1304 |doi= 10.1257/aer.97.4.1278|jstor=30034092 }}</ref> may arise when more words per article are devoted to one public figure than a rival public figure. Editors may dispute suspected biases and discuss controversial articles, sometimes at great length. Wales has noted the dangers of bias on controversial political topics or polarizing public figures.<ref name="en.wikipedia.org">{{cite web|url=https://en.wikipedia.org/wiki/Talk:James_Delingpole/Archive_1#Some_attention_to_this_article_likely_worthwhile |title=Talk:James Delingpole/Archive 1 – Wikipedia, the free encyclopedia |publisher=English Wikipedia |accessdate=2012-07-05}}</ref>

=== Citing Wikipedia ===
{{main|Reliability of Wikipedia}}

Most university [[lecturer]]s discourage students from citing any encyclopedia in [[Academia|academic work]], preferring [[primary source]]s;<ref name="WideWorldOfWikipedia" /> some specifically prohibit Wikipedia citations.<ref>{{cite doi|10.1145/1284621.1284635}}</ref><ref>{{cite news|first=Scott |last=Jaschik |title=A Stand Against Wikipedia |url=http://www.insidehighered.com/news/2007/01/26/wiki |publisher=Inside Higher Ed |date=January 26, 2007 |accessdate=January 27, 2007 }}</ref> Wales stresses that encyclopedias of any type are not usually appropriate to use as citeable sources, and should not be relied upon as authoritative.<ref name="AWorkInProgress" /> Wales once said he receives about ten [[e-mail]]s weekly from students saying they got failing grades on papers because they cited Wikipedia; he told the students they got what they deserved. "For God's sake, you're in college; don't cite the encyclopedia", he said.<ref>"Jimmy Wales", ''Biography Resource Center Online''. (Gale, 2006.)</ref>

In February 2007 an article in ''[[The Harvard Crimson]]'' newspaper reported that a few of the professors at [[Harvard University]] include Wikipedia in their [[syllabus|syllabi]], but that there is a split in their perception of using Wikipedia.<ref>Child, Maxwell L., [http://www.thecrimson.com/article.aspx?ref=517305 "Professors Split on Wiki Debate"], The Harvard Crimson, Monday, February 26, 2007.</ref> In June 2007 former president of the [[American Library Association]] [[Michael Gorman (librarian)|Michael Gorman]] condemned Wikipedia, along with [[Google]],<ref name="stothart" /> stating that academics who endorse the use of Wikipedia are "the intellectual equivalent of a dietitian who recommends a steady diet of Big Macs with everything". He also said that "a generation of intellectual sluggards incapable of moving beyond the Internet" was being produced at universities. He complains that the web-based sources are discouraging students from learning from the more rare texts which are found only on paper or subscription-only web sites. In the same article Jenny Fry (a research fellow at the [[Oxford Internet Institute]]) commented on academics who cite Wikipedia, saying that: "You cannot say children are intellectually lazy because they are using the Internet when academics are using search engines in their research. The difference is that they have more experience of being critical about what is retrieved and whether it is authoritative. Children need to be told how to use the Internet in a critical and appropriate way."<ref name="stothart" />

A Harvard law textbook, ''Legal Research in a Nutshell'' (2011), cites Wikipedia as a "general source" that "can be a real boon" in "coming up to speed in the law governing a situation" and, "while not authoritative, can provide basic facts as well as leads to more in-depth resources".<ref>{{cite book|last=Cohen|first=Morris|title=Legal Research in a Nutshell|coauthors=Olson, Kent|year=2010|publisher=Thomson Reuters|location=St. Paul, Minnesotta, USA|edition=10th|pages=32–34|isbn=978-0-314-26408-4}}</ref>

=== Explicit content ===
{{quote box
|align = right
|width=33%
|quote=Problem? What problem? So, you didn’t know that Wikipedia has a porn problem?
|source=Dr. Larry Sanger<ref name=autogenerated4 />}}

Wikipedia has been criticized for allowing information of graphic content. Articles depicting arguably objectionable content (such as [[feces]], [[corpses]], the [[human]] [[penis]] or [[vulva]]) contain graphic pictures and detailed information easily available to anyone with access to the internet, including children.

The site also includes [[sexual]] content such as images and videos of [[masturbation]] and [[ejaculation]] as well as photos from [[hardcore pornography|hardcore pornographic]] films in its articles.

The Wikipedia article about ''[[Virgin Killer]]'' – a 1976 album from [[music of Germany|German]] [[heavy metal music|heavy metal]] [[rock band|band]] [[Scorpions (band)|Scorpions]] – features a picture of the album's original cover, which depicts a naked [[prepubescent]] girl. The original release cover caused controversy and was replaced in some countries. In December 2008, access to the Wikipedia article ''[[Virgin Killer]]'' was [[Internet Watch Foundation and Wikipedia|blocked for four days]] by most [[Internet service provider]]s in the [[United Kingdom]], after it was reported by a member of the public as [[child pornography]],<ref>{{cite news|title=Brit ISPs censor Wikipedia over 'child porn' album cover|first=Cade|last=Metz|work=[[The Register]]|date=December 7, 2008|url=http://www.theregister.co.uk/2008/12/07/brit_isps_censor_wikipedia/|accessdate=May 10, 2009}}</ref> to the [[Internet Watch Foundation]] (IWF) which issues a stop list to Internet service providers. IWF, a non-profit, non-government-affiliated organization, later criticized the inclusion of the picture as "distasteful".<ref>{{cite news|title=Wikipedia Censorship Sparks Free Speech Debate|first=JR|last=Raphael|work=The Washington Post|date=December 10, 2008|url=http://www.washingtonpost.com/wp-dyn/content/article/2008/12/08/AR2008120803188.html|accessdate=May 10, 2009}}</ref>

In April 2010, [[Reporting of child pornography images on Wikimedia Commons|Sanger wrote a letter]] to the [[Federal Bureau of Investigation]], outlining his concerns that two categories of images on [[Wikimedia Commons]] contained child pornography, and were in violation of [[United States obscenity law|U.S. federal obscenity law]].<ref>{{cite news|last=Farrell|first=Nick|title=Wikipedia denies child abuse allegations: Co-founder grassed the outfit to the FBI |newspaper=The Inquirer|date=April 29, 2010|url=http://www.theinquirer.net/inquirer/news/1603521/wikipedia-denies-child-abuse-allegations|accessdate=October 9, 2010}}</ref> Sanger later clarified that the images, which were related to [[pedophilia]] and one about [[lolicon]], were not of real children, but said that they constituted "obscene visual representations of the sexual abuse of children", under the [[Child pornography laws in the United States#Section 1466A|PROTECT Act of 2003]].<ref name="The Register-April" /> That law bans photographic child pornography and cartoon images and drawings of children that are [[Obscenity#United States obscenity law|obscene under American law]].<ref name="The Register-April" /> Sanger also expressed concerns about access to the images on Wikipedia in schools.<ref>{{cite news|title=Wikipedia blasts co-founder's accusations of child porn on website|date=April 29, 2010|work=The Economic Times |location=India|url=http://economictimes.indiatimes.com/infotech/internet/Wikipedia-blasts-co-founders-accusations-of-child-porn-on-website/articleshow/5871943.cms|accessdate=April 29, 2010}}</ref> [[Wikimedia Foundation]] spokesman Jay Walsh strongly rejected Sanger's accusation,<ref name="AFP" /> saying that Wikipedia did not have "material we would deem to be illegal. If we did, we would remove it."<ref name="AFP" /> Following the complaint by Sanger, Wales deleted sexual images without consulting the community. After some editors who volunteer to maintain the site argued that the decision to delete had been made hastily, Wales voluntarily gave up some of the powers he had held up to that time as part of his co-founder status. He wrote in a message to the Wikimedia Foundation mailing-list that this action was "in the interest of encouraging this discussion to be about real philosophical/content issues, rather than be about me and how quickly I acted".<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/technology/10104946.stm |title=Wikimedia pornography row deepens as Wales cedes rights |publisher=BBC News |date=May 10, 2010 |accessdate=May 19, 2010}}</ref>

== Operation ==
=== Wikimedia Foundation and the Wikimedia chapters ===
{{main|Wikimedia Foundation}}

[[File:Wikimedia Foundation RGB logo with text.svg|thumb|upright|[[Wikimedia Foundation]] logo]]

Wikipedia is hosted and funded by the [[Wikimedia Foundation]], a non-profit organization which also operates Wikipedia-related projects such as [[Wiktionary]] and [[Wikibooks]]. The Wikimedia Foundation relies on public contributions and grants to fund its mission.<ref name="financialstatements">{{cite web | url = http://upload.wikimedia.org/wikipedia/foundation/a/ac/FINAL_10_11From_KPMG.pdf | title = Wikimedia Foundation – Financial Statements – June 30, 2011 and 2010 | publisher = Wikimedia Foundation }}</ref> The Wikimedia chapters, local associations of users and supporters of the Wikimedia projects, also participate in the promotion, development, and funding of the project.

=== Software and hardware ===
{{see also|MediaWiki}}

The operation of Wikipedia depends on [[MediaWiki]], a custom-made, [[free software|free]] and [[open source software|open source]] [[wiki software]] platform written in [[PHP]] and built upon the [[MySQL]] database system.<ref>{{cite web|url=http://www.nedworks.org/~mark/presentations/san/Wikimedia%20architecture.pdf |format=PDF|title=Wikimedia Architecture |author=Mark Bergman |publisher=Wikimedia Foundation |accessdate=June 27, 2008}}</ref> The software incorporates programming features such as a [[Macro (computer science)|macro language]], [[variable (programming)|variables]], a [[transclusion]] system for [[Web template|templates]], and [[URL redirection]]. MediaWiki is licensed under the [[GNU General Public License]] and it is used by all Wikimedia projects, as well as many other wiki projects. Originally, Wikipedia ran on [[UseModWiki]] written in [[Perl]] by Clifford Adams (Phase I), which initially required [[CamelCase]] for article hyperlinks; the present double bracket style was incorporated later. Starting in January 2002 (Phase II), Wikipedia began running on a [[PhpWiki|PHP wiki]] engine with a MySQL database; this software was custom-made for Wikipedia by [[Magnus Manske]]. The Phase II software was repeatedly modified to accommodate the [[Exponential growth|exponentially increasing]] demand. In July 2002 (Phase III), Wikipedia shifted to the third-generation software, MediaWiki, originally written by [[Lee Daniel Crocker]].

Several MediaWiki extensions are installed<ref>{{cite web
|url=https://en.wikipedia.org/wiki/Special:Version#Installed_extensions
|title=Version: Installed extensions}}</ref> to extend the functionality of the MediaWiki software.

In April 2005 a [[Lucene]] extension<ref>{{cite web
|url=https://en.wikipedia.org/wiki/Wikipedia:Wikipedia_Signpost/2005-04-18/Lucene_search
|title=Lucene search: Internal search function returns to service
|publisher=Wikimedia Foundation|author=Michael Snow|accessdate=February 26, 2009}}</ref><ref>{{cite web
|url=http://lists.wikimedia.org/pipermail/wikitech-l/2005-April/016297.html
|title=<nowiki>[Wikitech-l</nowiki>&#93; Lucene search|author=Brion Vibber|accessdate=February 26, 2009}}</ref> was added to MediaWiki's built-in search and Wikipedia switched from [[MySQL]] to Lucene for searching. The site currently uses Lucene Search 2.1,<ref>{{cite web
|url=http://www.mediawiki.org/wiki/Extension:Lucene-search
|title=Extension:Lucene-search|publisher=Wikimedia Foundation|accessdate=August 31, 2009}}</ref> which is written in [[Java (programming language)|Java]] and based on Lucene library 2.3.<ref>{{cite web
|url=http://svn.wikimedia.org/svnroot/mediawiki/branches/lucene-search-2.1/lib/
|title=mediawiki&nbsp;– Revision 55688: /branches/lucene-search-2.1/lib
|publisher=Wikimedia Foundation|accessdate=August 31, 2009}}</ref>

[[File:Wikimedia-servers-2010-12-28.svg|thumb|alt=Diagram showing flow of data between Wikipedia's servers. Twenty database servers talk to hundreds of Apache servers in the backend; the Apache servers talk to fifty squids in the frontend.|Overview of system architecture, December 2010. See [[:meta:Server layout diagrams|server layout diagrams on Meta-Wiki]].]]

Wikipedia receives between 25,000 and 60,000 page requests per second, depending on time of day.<ref>[[tools:~leon/stats/reqstats/reqstats-monthly.png|"Monthly request statistics"]], Wikimedia. Retrieved October 31, 2008.</ref> Page requests are first passed to a front-end layer of [[Squid (software)|Squid caching]] servers.<ref>{{cite web|url=http://domasmituzas.files.wordpress.com/2011/09/mysqluc2007-wikipedia-workbook.pdf |format=PDF|title=Wikipedia: Site internals, configuration, code examples and management issues |author=Domas Mituzas |publisher=MySQL Users Conference 2007 |accessdate=June 27, 2008}}</ref> Further statistics are available based on a publicly available 3-months Wikipedia access trace.<ref>{{cite web|url=http://www.globule.org/publi/WWADH_comnet2009.html |title=Wikipedia Workload Analysis for Decentralized Hosting |author=Guido Urdaneta, Guillaume Pierre and Maarten van Steen |publisher=Elsevier Computer Networks 53 (11), pp. 1830–1845, June 2009}}</ref> Requests that cannot be served from the Squid cache are sent to load-balancing servers running the [[Linux Virtual Server]] software, which in turn pass the request to one of the Apache web servers for page rendering from the database. The web servers deliver pages as requested, performing page rendering for all the language editions of Wikipedia. To increase speed further, rendered pages are cached in a distributed memory cache until invalidated, allowing page rendering to be skipped entirely for most common page accesses.

Wikipedia employed a single server until 2004, when the server setup was expanded into a distributed [[multitier architecture]]. In January 2005, the project ran on 39 [[Dedicated hosting service|dedicated servers]] in Florida. This configuration included a single master [[database server]] running [[MySQL]], multiple slave database servers, 21 [[web server]]s running the [[Apache HTTP Server]], and seven [[Squid (software)|Squid cache]] servers. Wikipedia currently runs on dedicated [[cluster (computing)|clusters]] of [[Linux]] servers (mainly [[Ubuntu (operating system)|Ubuntu]]),<ref>{{cite news |title=Wikipedia simplifies IT infrastructure by moving to one Linux vendor |first=Todd R. |last=Weiss |newspaper=[[Computerworld]] |date=October 9, 2008 |url=http://www.computerworld.com/s/article/9116787/Wikipedia_simplifies_IT_infrastructure_by_moving_to_one_Linux_vendor?taxonomyId=154&pageNumber=1&taxonomyName=Servers%20and%20Data%20Center |accessdate=November 1, 2008}}</ref><ref>{{cite news |title=Wikipedia adopts Ubuntu for its server infrastructure |first=Ryan |last=Paul |url=http://arstechnica.com/open-source/news/2008/10/wikipedia-adopts-ubuntu-for-its-server-infrastructure.ars |newspaper=[[Ars Technica]] |date=October 9, 2008 |accessdate=November 1, 2008}}</ref> with a few [[OpenSolaris]] machines for [[ZFS]]. As of December 2009, there were 300 in Florida and 44 in [[Amsterdam]].<ref name="servers" />

== Access to content ==
=== Content licensing ===
When the project was started in 2001, all text in Wikipedia was covered by [[GNU Free Documentation License]] (GFDL), a [[copyleft]] license permitting the redistribution, creation of derivative works, and commercial use of content while authors retain copyright of their work.<ref>{{srlink|Wikipedia:Copyrights}}</ref> GFDL was created for software manuals that come with [[free software]] programs that are licensed under [[GPL]]. This made it a poor choice for a general reference work; for example, the GFDL requires the reprints of materials from Wikipedia to come with a full copy of the GFDL license text. In December 2002, the [[Creative Commons license]] was released: it was specifically designed for creative works in general, not just for software manuals. The license gained popularity among bloggers and others distributing creative works on the Web. The Wikipedia project sought the switch to the Creative Commons.<ref>{{cite web|url=http://wikimediafoundation.org/wiki/Resolution:License_update
|title=Resolution:License update|year=2007|author=Walter Vermeir|publisher=Wikizine|accessdate=December 4, 2007}}</ref> Because the two licenses, GFDL and Creative Commons, were incompatible, in November 2008, following the request of the project, the [[Free Software Foundation]] (FSF) released a new version of GFDL designed specifically to allow Wikipedia to {{srlink|Wikipedia:Licensing update|relicense its content to CC BY-SA}} by August 1, 2009. (A new version of GFDL automatically covers Wikipedia contents.) In April 2009, Wikipedia and its sister projects held a community-wide referendum which decided the switch in June 2009.<ref name="voteresult" /><ref>{{cite web|url=http://meta.wikimedia.org/wiki/Licensing_update/Questions_and_Answers |title=Licensing update/Questions and Answers |work=Wikimedia Meta |publisher=Wikimedia Foundation |accessdate=February 15, 2009}}</ref><ref>{{cite web|url=http://meta.wikimedia.org/wiki/Licensing_update/Timeline |title=Licensing_update/Timeline |work=Wikimedia Meta |publisher=Wikimedia Foundation |accessdate=April 5, 2009}}</ref><ref>{{cite web|url=http://blog.wikimedia.org/2009/05/21/wikimedia-community-approves-license-migration/ |title=Wikimedia community approves license migration |work=Wikimedia Foundation |accessdate=May 21, 2009}}</ref>

The handling of media files (e.g., image files) varies across language editions. Some language editions, such as the English Wikipedia, include non-free image files under [[fair use]] doctrine, while the others have opted not to, in part due to the lack of fair use doctrines in their home countries (e.g., in [[Copyright law of Japan|Japanese copyright law]]). Media files covered by [[free content]] licenses (e.g., Creative Commons' CC BY-SA) are shared across language editions via [[Wikimedia Commons]] repository, a project operated by the Wikimedia Foundation. Wikipedia's accommodation of varying international copyright laws regarding images has led some to observe that its photographic coverage of topics lags behind the quality of the encyclopedic text.<ref>{{cite news |url= http://www.nytimes.com/2009/07/20/arts/20funny.html |title=Wikipedia May Be a Font of Facts, but It’s a Desert for Photos |date=July 19, 2009 |last=Cohen |first=Noam |publisher=New York Times |accessdate=March 9, 2013}}</ref>

The Wikimedia Foundation is not a licensor of content, but merely a hosting service for the contributors (and licensors) of the Wikipedia. This position has been successfully defended in court.<ref>{{cite news|url=http://www.reuters.com/article/internetNews/idUSL0280486220071102?feedType=RSS&feedName=internetNews|title=Wikipedia cleared in French defamation case|agency=Reuters|date=November 2, 2007|accessdate=November 2, 2007}}</ref><ref>{{cite web|url=http://arstechnica.com/news.ars/post/20080502-dumb-idea-suing-wikipedia-for-calling-you-dumb.html |title=Dumb idea: suing Wikipedia for calling you "dumb" |first=Nate |last=Anderson |publisher=Ars Technica |date=May 2, 2008 |accessdate=May 4, 2008}}</ref>

=== Methods of access ===
Because Wikipedia content is distributed under an open license, anyone can reuse or re-distribute it at no charge. The content of Wikipedia has been published in many forms, both online and offline, outside of the Wikipedia website.
* '''Web sites''' – Thousands of "[[mirror site]]s" exist that republish content from Wikipedia: two prominent ones, that also include content from other reference sources, are [[Reference.com]] and [[Answers.com]]. Another example is [[Wapedia]], which began to display Wikipedia content in a mobile-device-friendly format before Wikipedia itself did.
* '''Mobile apps''' – A variety of mobile apps provide access to Wikipedia on [[hand-held device]]s, including both [[Android (operating system)|Android]] and [[iOS]] devices (see [[Wikipedia App|Wikipedia apps]]). (See also [[#Mobile access|Mobile access]].)
* '''Search engines''' – Some [[web search engine]]s make special use of Wikipedia content when displaying search results: examples include [[Bing]] (via technology gained from [[Powerset (company)|Powerset]])<ref>[http://www.bing.com/community/site_blogs/b/search/archive/2009/07/27/researching-with-bing-reference.aspxResearching With Bing Reference], Bing Community blog, July 27, 2009</ref> and [[Duck Duck Go]].
* '''Compact discs, DVDs''' – Collections of Wikipedia articles have been published on [[optical disc]]s. An English version, [[Wikipedia CD Selection|2006 Wikipedia CD Selection]], contained about 2,000 articles.<ref>[http://www.wikipediaondvd.com "Wikipedia on DVD"]. Linterweb. Retrieved June 1, 2007. "Linterweb is authorized to make a commercial use of the Wikipedia trademark restricted to the selling of the Encyclopedia CDs and DVDs".</ref><ref>[http://www.wikipediaondvd.com/site.php?temp=buy "Wikipedia 0.5 Available on a CD-ROM"]. ''Wikipedia on DVD''. Linterweb. "The DVD or CD-ROM version 0.5 was commercially available for purchase." Retrieved June 1, 2007.</ref> The Polish-language version contains nearly 240,000 articles.<ref>{{cite web|url=http://meta.wikimedia.org/wiki/Polska_Wikipedia_na_DVD_%28z_Helionem%29/en |title=Polish Wikipedia on DVD |accessdate=December 26, 2008}}</ref> There are German and Spanish-language versions as well.<ref>{{cite web|url=http://de.wikipedia.org/wiki/Wikipedia:Wikipedia-Distribution |title=Wikipedia:DVD |accessdate=December 26, 2008}}</ref><ref>{{cite web|url=http://python.org.ar/pyar/Proyectos/CDPedia |title=CDPedia (Python Argentina) |accessdate=July 7, 2011}}</ref> Also, "Wikipedia for Schools", the Wikipedia series of CDs / DVDs produced by Wikipedians and [[SOS Children's Villages UK|SOS Children]], is a free, hand-checked, non-commercial selection from Wikipedia targeted around the [[National Curriculum (UK)|UK National Curriculum]] and intended to be useful for much of the English-speaking world.<ref>{{srlink|Wikipedia:Wikipedia CD Selection|Wikipedia CD Selection}}. Retrieved September 8, 2009.</ref> The project is available online; an equivalent print encyclopedia would require roughly 20 volumes.
* '''Books''' – There are efforts to put a select subset of Wikipedia's articles into printed book form.<ref>{{cite news|title=Wikipedia turned into book|url=http://www.telegraph.co.uk/news/newstopics/howaboutthat/5549589/Wikipedia-turned-into-book.html|archiveurl=http://www.webcitation.org/5jeCgQjpj|publisher=Telegraph Media Group|work=The Daily Telegraph |location=London |date=June 16, 2009|accessdate=September 8, 2009|archivedate=September 8, 2009 }}</ref><ref>{{cite web|url=http://schools-wikipedia.org |title=Wikipedia Selection for Schools |accessdate=2012-07-14}}</ref> Since 2009, tens of thousands of [[print on demand]] books which reproduced English, German, Russian and French Wikipedia articles have been produced by the American company [[Books LLC]] and by three [[Mauritius|Mauritian]] subsidiaries of the German publisher [[VDM Publishing|VDM]].<ref name="FAZ" />
* '''Semantic Web''' – The website [[DBpedia]], begun in 2007, is a project that extracts data from the infoboxes and category declarations of the English-language Wikipedia and makes it available in a queriable [[Semantic Web|semantic]] format, [[Resource Description Framework|RDF]]. The possibility has also been raised to have Wikipedia export its data directly in a semantic format, possibly by using the [[Semantic MediaWiki]] extension. Such an export of data could also help Wikipedia reuse its own data, both between articles on the same language Wikipedia and between different language Wikipedias.<ref>[http://technologyreview.com/web/25728/page2/ Wikipedia to Add Meaning to Its Pages], Tom Simonite, ''Technology Review'', July 7, 2010</ref>

Obtaining the full contents of Wikipedia for reuse presents challenges, since direct cloning via a [[web crawler]] is discouraged.<ref>{{srlink|Wikipedia:Database download|Wikipedia policies}} on data download</ref> Wikipedia publishes [[Wikipedia:Database download|"dumps"]] of its contents, but these are text-only; as of 2007 there is no dump available of Wikipedia's images.<ref>[[meta:Data dumps#Downloading Images|Data dumps: Downloading Images]], [[Wikimedia Meta-Wiki]]</ref>

Several languages of Wikipedia also maintain a [[WP:REFDESK|reference desk]], where volunteers answer questions from the general public. According to a study by Pnina Shachaf in the [[Journal of Documentation]], the quality of the Wikipedia reference desk is comparable to a standard [[library reference desk]], with an accuracy of 55%.<ref>[http://www.slis.indiana.edu/news/story.php?story_id=2064 "Wikipedia Reference Desk"], fetched February 17, 2010</ref>

==== Mobile access{{anchor|Wikipedia mobile access|Wikipedia mobile}} ====
:''See also: {{srlink|Help:Mobile access}}''

Wikipedia's original medium was for users to read and edit content using any standard [[web browser]] through a fixed [[internet access|internet connection]]. In addition, Wikipedia content is now accessible through the [[mobile web]].

Access to Wikipedia from mobile phones was possible as early as 2004, through the [[Wireless Application Protocol]] (WAP), via the [[Wapedia]] service. In June 2007 Wikipedia launched [http://en.mobile.wikipedia.org/ en.mobile.wikipedia.org], an official website for wireless devices. In 2009 a newer mobile service was officially released,<ref>{{cite web |title = Wikimedia Mobile is Officially Launched |work = Wikimedia Technical Blog |url = http://techblog.wikimedia.org/2009/06/wikimedia-mobile-launch/ |date = June 30, 2009 |accessdate =July 22, 2009 }}</ref> located at [http://en.m.wikipedia.org/ en.m.wikipedia.org], which caters to more advanced mobile devices such as the [[iPhone]], [[Android (operating system)|Android]]-based devices or [[WebOS]]-based devices. Several other methods of mobile access to Wikipedia have emerged. Many devices and applications optimise or enhance the display of Wikipedia content for mobile devices, while some also incorporate additional features such as use of Wikipedia [[metadata]] (See {{srlink|Wikipedia:Metadata}}), such as [[geoinformation]].<ref>{{cite web |url = http://androgeoid.com/2011/04/local-points-of-interest-in-wikipedia/ |title = Local Points Of Interest In Wikipedia |date = May 15, 2011 |accessdate =May 15, 2011 }}</ref><ref>{{cite web |url = http://www.ilounge.com/index.php/articles/comments/15802/ |title = iPhone Gems: Wikipedia Apps |date = November 30, 2008 |accessdate =July 22, 2008 }}</ref>

[[Wikipedia Zero]] is an initiative of the Wikimedia Foundation to expand the reach of the encyclopedia to the developing countries.<ref>{{cite web|last=Ellis |first=Justin |url=http://www.niemanlab.org/2013/01/wikipedia-plans-to-expand-mobile-access-around-the-globe-with-new-funding/ |title=Wikipedia plans to expand mobile access around the globe with new funding » Nieman Journalism Lab |publisher=www.niemanlab.org |date=2013-01-17 |accessdate=2013-04-22}}</ref>

== Impact ==
=== Sister projects – Wikimedia ===
Wikipedia has also spawned several sister projects, which are also wikis run by the [[Wikimedia Foundation]]: "In Memoriam: September 11 Wiki",<ref>{{cite web|url=http://www.sep11memories.org/wiki/In_Memoriam|archiveurl=http://web.archive.org/web/20110716003213/http://www.sep11memories.org/wiki/In_Memoriam|title=In Memoriam: September 11, 2001 |archivedate=July 16, 2011 |accessdate=February 6, 2007}}</ref> created in October 2002,<ref>[http://web.archive.org/web/20110718145925/http://www.sep11memories.org/index.php?title=In_Memoriam&oldid=1502 First edit to the wiki]. In Memoriam: September 11 wiki (October 28, 2002).</ref> detailed the [[September 11 attacks]]; [[Wiktionary]], a dictionary project, was launched in December 2002;<ref>{{cite web|url=http://meta.wikimedia.org/w/index.php?title=Wikimedia_News&diff=prev&oldid=4133 |title=Announcement of Wiktionary's creation |publisher=meta.wikimedia.org |accessdate=2012-07-14}}</ref> [[Wikiquote]], a collection of quotations, created a week after Wikimedia launched, and [[Wikibooks]], a collection of collaboratively written free textbooks and annotated texts. Wikimedia has since started a number of other projects, including: [[Wikimedia Commons]], a site devoted to free-knowledge multimedia; [[Wikinews]], for citizen journalism; and [[Wikiversity]], a project for the creation of free learning materials and the provision of online learning activities.<ref name="OurProjects" /> Of these, only Commons has had success comparable to that of Wikipedia. Another sister project of Wikipedia, [[Wikispecies]], is a catalogue of species. In 2012 [[Wikivoyage]], an editable travel guide, launched.

=== Impact on publishing ===
Some observers have stated that Wikipedia represents an economic threat to publishers of traditional encyclopedias, who may be unable to compete with a product that is essentially free.<ref>{{cite web|author=Christopher Caldwell|authorlink=Christopher Caldwell|date=14 June 2013|title=A chapter in the Enlightenment closes|url=http://www.ft.com/cms/s/0/ae22314a-d383-11e2-b3ff-00144feab7de.html|publisher=[[Financial Times|ft.com]]|accessdate=15 June 2013|quote=Bertelsmann did not resort to euphemism this week when it announced the end of the Brockhaus encyclopedia brand. Brockhaus had been publishing reference books for two centuries when the media group bought it in 2008. […] The internet has finished off Brockhaus altogether. […] What Germans like is Wikipedia.}}</ref> [[Nicholas G. Carr|Nicholas Carr]] wrote a 2005 essay, "The amorality of [[Web 2.0]]", that criticized websites with [[user-generated content]], like Wikipedia, for possibly leading to professional (and, in his view, superior) content producers going out of business, because "free trumps quality all the time". Carr wrote: "Implicit in the ecstatic visions of Web 2.0 is the hegemony of the amateur. I for one can't imagine anything more frightening."<ref>{{cite web| title = The amorality of Web 2.0
| url = http://www.roughtype.com/archives/2005/10/the_amorality_o.php | date=October 3, 2005
| work = Rough Type | accessdate=July 15, 2006 }}</ref> Others dispute the notion that Wikipedia, or similar efforts, will entirely displace traditional publications. For instance, [[Chris Anderson (writer)|Chris Anderson]], the editor-in-chief of ''[[Wired (magazine)|Wired Magazine]]'', wrote in ''[[Nature (journal)|Nature]]'' that the "[[wisdom of crowds]]" approach of Wikipedia will not displace top [[scientific journal]]s, with their rigorous [[peer review]] process.<ref>{{cite web| title = Technical solutions: Wisdom of the crowds | url = http://www.nature.com/nature/peerreview/debate/nature04992.html |work = Nature | accessdate=October 10, 2006 }}</ref>

=== Cultural significance ===
{{main|Wikipedia in culture}}
<!-- Every single cultural, media or Internet reference to Wikipedia does not need to be mentioned here and differentiation between what constitutes a matter of significance and what is run-of-the-mill is important when adding content here. -->

[[File:Time Between Edits Graph Jul05-Present.png|thumb|Graph showing the number of days between every 10,000,000th edit.]]

In addition to [[Logistic function|logistic growth]] in the number of its articles,<ref name="modelling" /> Wikipedia has steadily gained status as a general reference website since its inception in 2001.<ref name="comscore" /> According to [[Alexa Internet|Alexa]] and [[comScore]], Wikipedia is among the ten most visited websites worldwide.<ref name="AlexaTop500" /><ref name="comscoretop10" /> The growth of Wikipedia has been fueled by its dominant position in Google search results;<ref name="hoover" /> about 50% of search engine traffic to Wikipedia comes from Google,<ref name="hitwisegoogle" /> a good portion of which is related to academic research.<ref name="hitwiseAcademic" /> The number of readers of Wikipedia worldwide reached 365 million at the end of 2009.<ref name="365M" /> The [[Pew Research Center|Pew]] Internet and American Life project found that one third of US Internet users consulted Wikipedia.<ref name="Wikipedia users" /> In October 2006, the site was estimated to have a hypothetical market value of $580&nbsp;million if it ran advertisements.<ref name="Wikipedia valuation" />

Wikipedia's content has also been used in academic studies, books, conferences, and court cases.<ref name="Wikipedia in media" /><ref name="Bourgeois" /><ref>{{cite web|url=http://papers.ssrn.com/sol3/Delivery.cfm/SSRN_ID1346311_code835394.pdf?abstractid=1346311|title=Wikipedian Justice|format=PDF|accessdate=June 9, 2009}}</ref> The [[Parliament of Canada]]'s website refers to Wikipedia's article on [[same-sex marriage]] in the "related links" section of its "further reading" list for the [[Civil Marriage Act]].<ref>[http://www.parl.gc.ca/LegisInfo/BillDetails.aspx?billId=1585203&View=10 LEGISinfo – House Government Bill C-38 (38–1)], LEGISINFO (March 28, 2005)</ref> The encyclopedia's assertions are increasingly used as a source by organizations such as the U.S. federal courts and the [[World Intellectual Property Organization]]<ref name="WP_court_source" />&nbsp;– though mainly for ''supporting information'' rather than information decisive to a case.<ref name="Courts turn to Wikipedia" /> Content appearing on Wikipedia has also been cited as a source and referenced in some [[United States Intelligence Community|U.S. intelligence agency]] reports.<ref name="US Intelligence" /> In December 2008, the scientific journal [[RNA Biology]] launched a new section for descriptions of families of RNA molecules and requires authors who contribute to the section to also submit a draft article on the [[Rfam|RNA family]] for publication in Wikipedia.<ref name="Declan" />

Wikipedia has also been used as a source in journalism,<ref>{{cite news|title=Wikipedia in the Newsroom |url=http://www.ajr.org/Article.asp?id=4461 |date=February/March 2008 |publisher=American Journalism Review|first=Donna |last=Shaw |accessdate=February 11, 2008}}</ref><ref name="twsY23" /> often without attribution, and several reporters have been dismissed for plagiarizing from Wikipedia.<ref>Shizuoka newspaper plagiarized Wikipedia article ''Japan News Review'', July 5, 2007</ref><ref>[http://web.archive.org/web/20071015045010/http://www.mysanantonio.com/news/metro/stories/MYSA010307.02A.richter.132c153.html "Express-News staffer resigns after plagiarism in column is discovered"], ''[[San Antonio Express-News]]'', January 9, 2007.</ref><ref>[http://archives.starbulletin.com/2006/01/13/news/story03.html "Inquiry prompts reporter's dismissal"], ''[[Honolulu Star-Bulletin]]'', January 13, 2007.</ref>

In July 2007 Wikipedia was the focus of a 30-minute documentary on [[BBC Radio 4]]<ref>{{cite web|url=http://www.bbc.co.uk/radio4/factual/pip/efv21/|title=Radio 4 documentary, BBC}}</ref> which argued that, with increased usage and awareness, the number of references to Wikipedia in popular culture is such that the word is one of a select band of 21st-century nouns that are so familiar ([[Google]], Facebook, YouTube) that they no longer need explanation and are on a par with such 20th-century words as [[The Hoover Company|hoovering]] or [[Coca-Cola]].

On September 28, 2007, [[Italy|Italian]] politician [[Franco Grillini]] raised a parliamentary question with the minister of cultural resources and activities about the necessity of [[freedom of panorama]]. He said that the lack of such freedom forced Wikipedia, "the seventh most consulted website", to forbid all images of modern Italian buildings and art, and claimed this was hugely damaging to tourist revenues.<ref>{{cite web|url=http://www.grillini.it/show.php?4885|title=Comunicato stampa. On. Franco Grillini. Wikipedia. Interrogazione a Rutelli. Con "diritto di panorama" promuovere arte e architettura contemporanea italiana. Rivedere con urgenza legge copyright|date=October 12, 2007 |language=Italian |trans_title=Press release. Honorable Franco Grillini. Wikipedia. Interview with Rutelli about the "right to view" promoting contemporary art and architecture of Italy. Review with urgency copyright law |accessdate=December 26, 2008}}</ref>

[[File:Quadriga-verleihung-rr-02.jpg|thumb|[[Jimmy Wales]] receiving the [[Quadriga (award)|Quadriga]] ''A Mission of Enlightenment'' award.]]

On September 16, 2007, ''[[The Washington Post]]'' reported that Wikipedia had become a focal point in the [[United States presidential election, 2008|2008 U.S. election campaign]], saying: "Type a candidate's name into Google, and among the first results is a Wikipedia page, making those entries arguably as important as any ad in defining a candidate. Already, the presidential entries are being edited, dissected and debated countless times each day."<ref>{{cite news
|url=http://www.washingtonpost.com/wp-dyn/content/article/2007/09/16/AR2007091601699_pf.html
|title=On Wikipedia, Debating 2008 Hopefuls' Every Facet
|author=Jose Antonio Vargas
|work=The Washington Post
|date=September 17, 2007
|accessdate=December 26, 2008}}
</ref> An October 2007 [[Reuters]] article, titled "Wikipedia page the latest status symbol", reported the recent phenomenon of how having a Wikipedia article vindicates one's notability.<ref>{{cite news
|url=http://www.reuters.com/article/domesticNews/idUSN2232893820071022?sp=true|title=Wikipedia page the latest status symbol|author=Jennifer Ablan|agency=Reuters|date=October 22, 2007|accessdate=October 24, 2007}}</ref>

Active participation also has an impact. Law students have been assigned to write Wikipedia articles as an exercise in clear and succinct writing for an uninitiated audience.<ref>{{cite journal|title=Engaging with the World: Students of Comparative Law Write for Wikipedia|publisher=Legal Education Review|volume=19|issue=1 and 2|year=2009|pages=83–98|author=Witzleb, Normann|postscript=}}</ref>

==== Awards ====
Wikipedia won two major awards in May 2004.<ref>[[m:Trophy box|"Trophy box"]], {{srlink|Wikipedia:Meta|Meta-Wiki}} (March 28, 2005).</ref> The first was a Golden Nica for Digital Communities of the annual [[Prix Ars Electronica]] contest; this came with a €10,000 (£6,588; $12,700) grant and an invitation to present at the PAE Cyberarts Festival in [[Austria]] later that year. The second was a Judges' [[Webby Award]] for the "community" category.<ref>{{cite web|url=http://www.webbyawards.com/webbys/winners-2004.php|title=Webby Awards 2004|publisher=The International Academy of Digital Arts and Sciences|year=2004|archiveurl=http://web.archive.org/web/20110722174246/http://www.webbyawards.com/webbys/winners-2004.php|archivedate=July 22, 2011}}</ref> Wikipedia was also nominated for a "Best Practices" Webby award. On January 26, 2007, Wikipedia was also awarded the fourth highest brand ranking by the readers of “brandchannel.com”, receiving 15% of the votes in answer to the question "Which brand had the most impact on our lives in 2006?"<ref>{{cite news|first=Anthony |last=Zumpano |title=Similar Search Results: Google Wins |url=http://www.brandchannel.com/features_effect.asp?pf_id=352 |publisher=Interbrand |date=January 29, 2007 |accessdate=January 28, 2007 }}</ref>

In September 2008, Wikipedia received [[Quadriga (award)|Quadriga]] ''A Mission of Enlightenment'' award of Werkstatt Deutschland along with [[Boris Tadić]], [[Eckart Höfling]], and [[Peter Gabriel]]. The award was presented to Wales by [[David Weinberger]].<ref>{{cite web|url=http://loomarea.com/die_quadriga/e/index.php?title=Award_2008|title=Die Quadriga&nbsp;– Award 2008 |accessdate=December 26, 2008}}</ref>

==== Satire ====
[[File:White Nerdy YOU SUCK cropped.jpg|thumb|left|alt=Wikipedia page on Atlantic Records being edited to read: "You suck!"|Wikipedia shown in [["Weird Al" Yankovic]]'s music video for his song "[[White & Nerdy]]".]]

Many parody Wikipedia's openness and susceptibility to inserted inaccuracies, with characters vandalizing or modifying the online encyclopedia project's articles.

Comedian [[Stephen Colbert]] has parodied or referenced Wikipedia on numerous episodes of his show ''[[The Colbert Report]]'' and coined the related term ''[[wikiality]]'', meaning "together we can create a reality that we all agree on—the reality we just agreed on".<ref name="wikiality" /> Another example can be found in a front-page article in ''[[The Onion]]'' in July 2006, with the title "Wikipedia Celebrates 750 Years of American Independence".<ref>{{cite web|url=http://www.theonion.com/content/node/50902 |title=Wikipedia Celebrates 750 Years Of American Independence |accessdate=October 15, 2006 |year=2006 |work=[[The Onion]]}}</ref> "[[My Number One Doctor]]", a 2007 episode of the [[television|TV]] show ''[[Scrubs (TV series)|Scrubs]]'', played on the perception that Wikipedia is an unreliable reference tool with a scene in which [[Perry Cox|Dr. Perry Cox]] reacts to a patient who says that a Wikipedia article indicates that the [[raw food diet]] reverses the effects of [[bone cancer]] by retorting that the same editor who wrote that article also wrote the [[List of Battlestar Galactica (2004 TV series) episodes|''Battlestar Galactica'' episode guide]].<ref>Bakken, Janae. "[[My Number One Doctor]]"; ''[[Scrubs (TV series)|Scrubs]]''; [[American Broadcasting Company|ABC]]; December 6, 2007.</ref>

In 2008, the comedic website [[CollegeHumor]] produced a video sketch named "Professor Wikipedia", in which the fictitious Professor Wikipedia instructs a class with a medley of unverifiable and occasionally absurd statements.<ref>{{cite web|url=http://www.collegehumor.com/video/3581424/professor-wikipedia |title=Professor Wikipedia – CollegeHumor Video |publisher=CollegeHumor |date=November 17, 2009 |accessdate=April 19, 2011}}</ref>

The [[Dilbert]] comic strip from May 8, 2009, concludes with Topper suggesting that the others check Wikipedia in a few minutes (after he's had a chance to edit it in order to back up a preposterous claim regarding a gallstone).<ref>{{cite web|url=http://dilbert.com/strips/comic/2009-05-08/ |title=Dilbert comic strip for 05/08/2009 from the official Dilbert comic strips archive. |publisher=Universal Uclick |date=May 8, 2009 |accessdate=March 10, 2013}}</ref>

In July 2009, [[BBC Radio 4]] broadcast a comedy series called ''[[Bigipedia]]'', which was set on a website which was a parody of Wikipedia. Some of the sketches were directly inspired by Wikipedia and its articles.<ref>{{cite web|url=http://www.comedy.org.uk/guide/radio/bigipedia/interview/|title=Interview With Nick Doody and Matt Kirshen|publisher=[[British Comedy Guide]]|accessdate=July 31, 2009}}</ref>

In 2010, comedian Daniel Tosh encouraged viewers of his show, ''[[Tosh.0]]'', to visit the show's Wikipedia article and edit it at will. On a later episode, he commented on the edits to the article, most of them offensive, which had been made by the audience and had prompted the article to be locked from editing.<ref>[http://tosh.comedycentral.com/blog/2010/02/03/your-wikipedia-entries/ ''Your Wikipedia Entries''], ''[[Comedy Central]]'' (February 3, 2010)</ref><ref>[http://tosh.comedycentral.com/video-clips/wikipedia-updates ''Wikipedia Updates''], ''[[Comedy Central]]'' (February 3, 2010)</ref>

=== Scientific use ===
In [[computational linguistics]], [[information retrieval]] and [[natural language processing]], Wikipedia has seen widespread use as a [[text corpus|corpus]] for linguistic research. In particular, it commonly serves as a target knowledge base for the [[entity linking]] problem, which is then called "wikification",<ref name="wikify">Rada Mihalcea
and Andras Csomai (2007). [http://www.cs.unt.edu/~rada/papers/mihalcea.cikm07.pdf Wikify! Linking Documents to Encyclopedic Knowledge]. Proc. CIKM.</ref>
and to the related problem of [[word sense disambiguation]].<ref>David Milne and Ian H. Witten (2008). Learning to link with Wikipedia. Proc. CIKM.</ref>
Methods similar to wikification can in turn be used to find "missing" links in Wikipedia.<ref>Sisay Fissaha Adafre and [[Maarten de Rijke]] (2005). [http://staff.science.uva.nl/~mdr/Publications/Files/linkkdd2005.pdf Discovering missing links in Wikipedia]. Proc. LinkKDD.</ref>

== Related projects ==
A number of interactive multimedia encyclopedias incorporating entries written by the public existed long before Wikipedia was founded. The first of these was the 1986 [[BBC Domesday Project]], which included text (entered on [[BBC Micro]] computers) and photographs from over 1&nbsp;million contributors in the UK, and covered the geography, art, and culture of the UK. This was the first interactive multimedia encyclopedia (and was also the first major multimedia document connected through internal links), with the majority of articles being accessible through an interactive map of the UK. The user interface and part of the content of the Domesday Project were emulated on a website until 2008.<ref name="Domesday Project" /> One of the most successful early online encyclopedias incorporating entries by the public was [[h2g2]], which was created by [[Douglas Adams]]. The h2g2 encyclopedia is relatively light-hearted, focusing on articles which are both witty and informative. [[Everything2]] was created in 1998. All of these projects had similarities with Wikipedia, but were not wikis and neither gave full editorial privileges to public users.

[[GNE (encyclopedia)|GNE]], an encyclopedia which was not a wiki, also created in January 2001, co-existed with Nupedia and Wikipedia early in its history; however, it has been retired.<ref name="stallman1999" />

Other websites centered on collaborative [[knowledge base]] development have drawn inspiration from Wikipedia. Some, such as [[Susning.nu]], [[Enciclopedia Libre Universal en Español|Enciclopedia Libre]], [[Hudong]], and [[Baidu Baike]] likewise employ no formal review process, although some like [[Conservapedia]] are not as open. Others use more traditional [[peer review]], such as [[Encyclopedia of Life]] and the online wiki encyclopedias [[Scholarpedia]] and [[Citizendium]]. The latter was started by Sanger in an attempt to create a reliable alternative to Wikipedia.<ref name="Orlowski18" /><ref name="JayLyman" /> [[Scholarpedia]] also focuses on ensuring high quality.

== See also ==
{{meta|List of Wikipedias}}

{{portal|Internet}}
* [[Outline of Wikipedia]] – guide to the subject of ''Wikipedia'' presented as a [[tree structure]]d list of its subtopics; for an outline of the contents of ''Wikipedia'', see [[Portal:Contents/Outlines]]
* [[Conflict of interest editing on Wikipedia]]
* [[Democratization of knowledge]]
* [[Interpedia]], an early proposal for a collaborative [[Internet]] encyclopedia
* [[List of online encyclopedias]]
* [[List of wikis]]
* [[Network effect]]
* [[QRpedia]] – multilingual, mobile interface to Wikipedia
* [[VisualEditor]]
* [[Wikipedia Review]]

'''Special searches'''
* {{In title|Wikipedia}}
* {{lookfrom|Wikipedia}}

== References ==
===Notes===
{{Reflist|30em|refs=
<ref name=modelling>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:Modelling_Wikipedia%27s_growth |title=Wikipedia:Modelling Wikipedia's growth |accessdate=December 22, 2007}}</ref>

<ref name=comscore>{{cite web|url=http://www.comscore.com/press/release.asp?press=849 |title=694 Million People Currently Use the Internet Worldwide According To comScore Networks |date=May 4, 2006 |publisher=comScore |accessdate=December 16, 2007 |quote=Wikipedia has emerged as a site that continues to increase in popularity, both globally and in the U.S.|archiveurl=http://web.archive.org/web/20080730011713/http://www.comscore.com/press/release.asp?press=849|archivedate=July 30, 2008}}</ref>

<ref name=comscoretop10>{{cite web|url=http://www.comscore.com/press/data/top_worldwide_properties.asp |archiveurl=http://web.archive.org/web/20080124110845/www.comscore.com/press/data/top_worldwide_properties.asp |archivedate=January 15, 2008 |title=comScore Data |month=December | year=2007 |accessdate=January 19, 2008}}</ref>

<ref name=hoover>{{cite journal|url=http://www.hoover.org/publications/ednext/16111162.html |archiveurl=http://web.archive.org/web/20080327230211/http://www.hoover.org/publications/ednext/16111162.html |archivedate=March 27, 2008 |title=Wikipedia or Wickedpedia? |journal=Hoover Institution |first=Michael J. |last= Petrilli |volume=8 |issue=2 |accessdate=March 21, 2008}}</ref>

<ref name=hitwisegoogle>{{cite web|url=http://weblogs.hitwise.com/leeann-prescott/2007/02/wikipedia_traffic_sources.html |title=Google Traffic To Wikipedia up 166% Year over Year |publisher=Hitwise |date=February 16, 2007 |accessdate=December 22, 2007}}</ref>

<ref name=hitwiseAcademic>{{cite web|url=http://weblogs.hitwise.com/leeann-prescott/2006/10/wikipedia_and_academic_researc.html |title=Wikipedia and Academic Research |publisher=Hitwise |date=October 17, 2006 |accessdate=February 6, 2008}}</ref>

<ref name="Wikipedia users">{{cite web|first=Lee |last=Rainie |coauthors=Bill Tancer |title=Wikipedia users |publisher=Pew Research Center |work=Pew Internet & American Life Project |date=December 15, 2007 |quote=36% of online American adults consult Wikipedia. It is particularly popular with the well-educated and current college-age students.|url=http://www.pewinternet.org/pdfs/PIP_Wikipedia07.pdf |format=PDF |accessdate=December 15, 2007 |archiveurl=http://web.archive.org/web/20080306031354/http://www.pewinternet.org/pdfs/PIP_Wikipedia07.pdf |archivedate=March 6, 2008 }}</ref>

<ref name="Wikipedia valuation">{{cite web |url=http://www.watchmojo.com/web/blog/?p=626 |title=What is Wikipedia.org's Valuation? |first=Ashkan |last=Karbasfrooshan |date=October 26, 2006 |accessdate=December 1, 2007}}</ref>

<ref name="Wikipedia in media">{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:Wikipedia_in_the_media |title=Wikipedia:Wikipedia in the media |work=Wikipedia |accessdate=December 26, 2008}}</ref>

<ref name="Bourgeois">{{cite web|url=http://www.ca11.uscourts.gov/opinions/ops/200216886.pdf|title=Bourgeois ''et al.'' v. Peters ''et al.''|format=PDF|accessdate=February 6, 2007}}</ref>

<ref name="Courts turn to Wikipedia">{{cite news|last=Cohen |first=Noam |date=January 29, 2007 |title=Courts Turn to Wikipedia, but Selectively |work=The New York Times |url=http://www.nytimes.com/2007/01/29/technology/29wikipedia.html |accessdate=December 26, 2008}}</ref>

<ref name="US Intelligence">{{cite web|url=http://www.fas.org/blog/secrecy/2007/03/the_wikipedia_factor_in_us_int.html |title=The Wikipedia Factor in U.S. Intelligence |first=Steven | last= Aftergood |publisher=Federation of American Scientists Project on Government Secrecy |date=March 21, 2007 |accessdate=April 14, 2007}}</ref>

<ref name="Declan">{{cite journal| last = Butler | first = Declan | date=December 16, 2008 | title = Publish in Wikipedia or perish | journal = Nature News | doi = 10.1038/news.2008.1312 }}</ref>

<ref name=Sidener>{{cite news|url=http://www.signonsandiego.com/uniontrib/20041206/news_mz1b6encyclo.html|author=Jonathan Sidener|title=Everyone's Encyclopedia|work=[[U-T San Diego]]|accessdate=October 15, 2006}}</ref>

<ref name=MiliardWho>{{cite news|url=http://www.cityweekly.net/utah/article-5129-feature-wikipediots-who-are-these-devoted-even-obsessive-contributors-to-wikipedia.html|author=Mike Miliard|title=Wikipediots: Who Are These Devoted, Even Obsessive Contributors to Wikipedia?|work=[[Salt Lake City Weekly]]|date=March 1, 2008|accessdate=December 18, 2008}}</ref>

<ref name=Time2006>{{cite news| date=December 13, 2006| url= http://www.time.com/time/magazine/article/0,9171,1569514,00.html |title= Time's Person of the Year: You |work=Time |publisher=Time |accessdate=December 26, 2008 | first=Lev | last=Grossman}}</ref>

<ref name=Dee>{{cite news| url = http://www.nytimes.com/2007/07/01/magazine/01WIKIPEDIA-t.html | title = All the News That's Fit to Print Out|author=Jonathan Dee|work = The New York Times Magazine|date=July 1, 2007|accessdate=December 1, 2007}}</ref>

<ref name=Lih>{{cite journal|author=Andrew Lih|title=Wikipedia as Participatory Journalism: Reliable Sources? Metrics for Evaluating Collaborative Media as a News Resource|journal=5th International Symposium on Online Journalism|location=University of Texas at Austin|date=April 16, 2004|url=http://jmsc.hku.hk/faculty/alih/publications/utaustin-2004-wikipedia-rc2.pdf|format=PDF|accessdate=October 13, 2007}}</ref>

<ref name="AcademiaAndWikipedia">{{cite web|author=Danah Boyd|url=http://many.corante.com/archives/2005/01/04/academia_and_wikipedia.php|title=Academia and Wikipedia|work=Many 2 Many: A Group [[Blog|Weblog]] on Social Software|publisher=Corante |date=January 4, 2005|accessdate=December 18, 2008|quote=[The author, Danah Boyd, describes herself as] an expert on social media[,] ... a doctoral student in the School of Information at the [[University of California, Berkeley]] [,] and a fellow at the [[Harvard University]] [[Berkman Center for Internet & Society]] [at [[Harvard Law School]].]}}</ref>

<ref name="MIT_IBM_study">{{cite journal|author=Fernanda B. Viégas, Martin Wattenberg, and Kushal Dave|url=http://alumni.media.mit.edu/~fviegas/papers/history_flow.pdf|title=Studying Cooperation and Conflict between Authors with History Flow Visualizations|journal=Proceedings of the [[CHI (conference)|ACM Conference on Human Factors in Computing Systems (CHI)]]|publisher=ACM [[SIGCHI]]|pages=575–582|location=Vienna, Austria|year=2004|format=PDF|doi=10.1145/985921.985953|isbn=1-58113-702-8|accessdate=January 24, 2007}}</ref>

<ref name="CreatingDestroyingAndRestoringValue">{{cite journal|author=Reid Priedhorsky, Jilin Chen, Shyong (Tony) K. Lam, Katherine Panciera, Loren Terveen, and John Riedl (GroupLens Research, Department of Computer Science and Engineering, [[University of Minnesota]])|title =Creating, Destroying, and Restoring Value in Wikipedia|journal =[[Association for Computing Machinery]] GROUP '07 conference proceedings|location =[[Sanibel Island]], [[Florida]]|date=November 4, 2007|url =http://www-users.cs.umn.edu/~reid/papers/group282-priedhorsky.pdf|format=PDF|accessdate=October 13, 2007}}</ref>

<ref name="stallman1999">{{cite web |url=http://www.gnu.org/encyclopedia/encyclopedia.html |title=The Free Encyclopedia Project|author=Richard M. Stallman|authorlink=Richard Stallman|date=June 20, 2007|publisher=Free Software Foundation |accessdate=January 4, 2008}}</ref>

<ref name=autogenerated1>{{cite news|url=http://www.signonsandiego.com/uniontrib/20041206/news_mz1b6encyclo.html|author=Jonathan Sidener|title=Everyone's Encyclopedia|date=December 6, 2004|work=[[U-T San Diego]]|accessdate=October 15, 2006}}</ref>

<ref name=Meyers>{{cite news|first=Peter |last=Meyers|title=Fact-Driven? Collegial? This Site Wants You |url=http://query.nytimes.com/gst/fullpage.html?res=9800E5D6123BF933A1575AC0A9679C8B63&n=Top%2fReference%2fTimes%20Topics%2fSubjects%2fC%2fComputer%20Software |work=The New York Times |date=September 20, 2001|quote='I can start an article that will consist of one paragraph, and then a real expert will come along and add three paragraphs and clean up my one paragraph,' said Larry Sanger of Las Vegas, who founded Wikipedia with Mr. Wales.|accessdate=November 22, 2007}}</ref>

<ref name=SangerMemoir>{{cite news|first=Larry |last=Sanger |title=The Early History of Nupedia and Wikipedia: A Memoir |date=April 18, 2005 |work=Slashdot |url=http://features.slashdot.org/features/05/04/18/164213.shtml|accessdate=December 26, 2008}}</ref>

<ref name=Sanger>{{cite news|first=Larry |last=Sanger|title=Wikipedia Is Up!|date=January 17, 2001 |url=http://www.nupedia.com/pipermail/nupedia-l/2001-January/000684.html|accessdate=December 26, 2008|archiveurl=http://web.archive.org/web/20010506042824/http://www.nupedia.com/pipermail/nupedia-l/2001-January/000684.html|archivedate=May 6, 2001}}</ref>

<ref name=WikipediaHome>{{cite web|url=http://www.wikipedia.com/|archiveurl=http://web.archive.org/web/20010331173908/http://www.wikipedia.com/|archivedate=March 31, 2001|title=Wikipedia: HomePage|accessdate=March 31, 2001}}</ref>

<ref name="NPOV">"[https://en.wikipedia.org/w/index.php?title=Wikipedia:Neutral_point_of_view&oldid=102236018 Wikipedia:Neutral point of view], Wikipedia (January 21, 2007).</ref>

<ref name="EB_encyclopedia">{{cite encyclopedia |title=Encyclopedias and Dictionaries |encyclopedia=Encyclopædia Britannica, 15th ed. |year=2007 |volume=18 |pages=257–286 <!-- |author1=<Please add first missing authors to populate metadata.> -->}}</ref>

<ref name=Shirky>{{cite book|author= Clay Shirky|authorlink=Clay Shirky|title=Here Comes Everybody: The Power of Organizing Without Organizations|date=February 28, 2008|publisher=The Penguin Press via Amazon Online Reader|url=http://www.amazon.com/gp/reader/1594201536/ref=sib_dp_srch_pop?v=search-inside&keywords=spanish&go.x=0&go.y=0&go=Go%21 |isbn=1-59420-153-6|page=273 |accessdate=December 26, 2008}}</ref>

<ref name=NOR>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:No_original_research |title=Wikipedia:No original research |accessdate=February 13, 2008|quote=Wikipedia does not publish original thought}}</ref>

<ref name=autogenerated2>{{cite web|url=https://en.wikipedia.org/wiki/Wikipedia:Neutral_point_of_view|title=Wikipedia:Neutral_point_of_view|quote=All Wikipedia articles and other encyclopedic content must be written from a neutral point of view, representing significant views fairly, proportionately and without bias.|accessdate=February 13, 2008 }}</ref>

<ref name="voteresult">[[meta:Licensing update/Result|Wikimedia]]</ref>

<ref name=FAZ>{{cite web |last=Thiel |first=Thomas |title=Wikipedia und Amazon: Der Marketplace soll es richten |work=Frankfurter Allgemeine Zeitung |publisher=[[Frankfurter Allgemeine Zeitung]] |language=German |date=September 27, 2010 |url=http://www.faz.net/s/RubCF3AEB154CE64960822FA5429A182360/Doc~E7A20980B9C0D46E99A9F60BC09506343~ATpl~Ecommon~Scontent.html |accessdate=December 6, 2010 }}</ref>

<ref name="Seigenthaler">{{cite news |url=http://www.usatoday.com/news/opinion/editorials/2005-11-29-wikipedia-edit_x.htm |last=Seigenthaler |first=John |title=A False Wikipedia 'biography' |date=November 29, 2005 |work=USA Today |accessdate=December 26, 2008}}</ref>

<ref name="Torsten_Kleinz">{{cite news |first=Torsten |last=Kleinz |title=World of Knowledge |work=Linux Magazine |quote= The Wikipedia's open structure makes it a target for trolls and vandals who malevolently add incorrect information to articles, get other people tied up in endless discussions, and generally do everything to draw attention to themselves.|date=February 2005 |url=http://w3.linux-magazine.com/issue/51/Wikipedia_Encyclopedia.pdf |format=PDF |accessdate=July 13, 2007 }}</ref>

<ref name="DeathByWikipedia">{{cite news |title=Death by Wikipedia: The Kenneth Lay Chronicles |url=http://www.washingtonpost.com/wp-dyn/content/article/2006/07/08/AR2006070800135.html |first=Frank |last=Ahrens |work=The Washington Post |date=July 9, 2006 |accessdate=November 1, 2006}}</ref>

<ref name="wikiality">{{cite news |title=Wikiality |url=http://www.colbertnation.com/the-colbert-report-videos/72347/july-31-2006/the-word---wikiality |author=Stephen Colbert |date=July 30, 2006 |accessdate=December 26, 2008}}</ref>

<ref name="Seeing Corporate Fingerprints">{{cite news |url=http://www.nytimes.com/2007/08/19/technology/19wikipedia.html |title=Seeing Corporate Fingerprints From the Editing of Wikipedia |first=Katie |last=Hafner |work=The New York Times |date=August 19, 2007 |accessdate=December 26, 2008}}</ref>

<ref name=Taylor>{{cite news|url=http://in.reuters.com/article/technologyNews/idINIndia-32865420080405|title=China allows access to English Wikipedia|agency=Reuters|author=Sophie Taylor|date=April 5, 2008|accessdate=July 29, 2008}}</ref>

<ref name=Kittur2009>Kittur, A., Chi, E. H., and Suh, B. 2009. [http://www-users.cs.umn.edu/~echi/papers/2009-CHI2009/p1509.pdf What’s in Wikipedia? Mapping Topics and Conflict Using Socially Annotated Category Structure]. In Proceedings of the 27th international Conference on Human Factors in Computing Systems (Boston, Massachusetts, USA, April 4&nbsp;– 9, 2009). CHI '09. ACM, New York, USA, 1509–1512.</ref>

<ref name=Rosenzweig>{{cite journal|author=Roy Rosenzweig|title=Can History be Open Source? Wikipedia and the Future of the Past|journal=The Journal of American History|volume=93|issue=1|month=June | year=2006|pages=117–146|url=http://chnm.gmu.edu/essays-on-history-new-media/essays/?essayid=42|accessdate=August 11, 2006|doi=10.2307/4486062}} (Center for History and New Media.)</ref>

<ref name="WikipediaWatch">Public Information Research, Wikipedia Watch</ref>

<ref name="McHenry_2004">[[Robert McHenry]], [http://www.techcentralstation.com/111504A.html "The Faith-Based Encyclopedia"], [[TCS Daily|Tech Central Station]], November 15, 2004.</ref>

<ref name="WideWorldOfWikipedia">{{cite web| title = Wide World of Wikipedia | publisher = The Emory Wheel | url = http://www.emorywheel.com/detail.php?n=17902 | date=April 21, 2006 | accessdate=October 17, 2007 }}</ref>

<ref name="AWorkInProgress">{{cite news|first=Burt |last=Helm |title= Wikipedia: "A Work in Progress" |url= http://www.businessweek.com/technology/content/dec2005/tc20051214_441708.htm |work=Bloomberg BusinessWeek |date=December 14, 2005 |accessdate=January 29, 2007 }}</ref>

<ref name="GilesJ2005Internet">{{cite journal | author = Jim Giles | title = Internet encyclopedias go head to head | journal = [[Nature (journal)|Nature]]
| volume = 438 | issue = 7070 | pages = 900–901 | month = December | year = 2005 | pmid = 16355180
| url = http://www.nature.com/nature/journal/v438/n7070/full/438900a.html | doi = 10.1038/438900a | authorlink = Jim Giles (reporter) | bibcode=2005Natur.438..900G}}
The study (that was not in itself peer reviewed) was cited in several news articles; e.g.:
* {{cite news | title=Wikipedia survives research test | date=December 15, 2005 |publisher=BBC | url=http://news.bbc.co.uk/2/hi/technology/4530930.stm}}
</ref>

<ref name="corporate.britannica.com">[http://corporate.britannica.com/britannica_nature_response.pdf Fatally Flawed: Refuting the recent study on encyclopedic accuracy by the journal Nature], Encyclopædia Britannica, March 2006</ref>

<ref name="stothart">Chloe Stothart, [http://www.timeshighereducation.co.uk/story.asp?sectioncode=26&storycode=209408 Web threatens learning ethos], ''The Times Higher Education Supplement'', 2007, 1799 (June 22), page 2</ref>

<ref name="wwplagiarism">{{cite web|title=Plagiarism by Wikipedia editors|url=http://www.wikipedia-watch.org/psamples.html|publisher=Wikipedia Watch|date=October 27, 2006|archiveurl=http://www.webcitation.org/5lXiLbptk|archivedate=November 25, 2009}}</ref>

<ref name="The Register-April">{{cite news|url=http://www.theregister.co.uk/2010/04/09/sanger_reports_wikimedia_to_the_fbi/|work=The Register|date=April 9, 2010|first=Cade|last=Metz|title=Wikifounder reports Wikiparent to FBI over 'child porn'|accessdate=April 19, 2010}}</ref>

<ref name=AFP>{{cite news|url=http://www.google.com/hostednews/afp/article/ALeqM5iPnPNqEkWafeVXnPIWfaS2wN6XSQ|title=Wikipedia blasts talk of child porn at website|date=April 28, 2010|agency={{lang|fr|Agence France-Presse}}|accessdate=April 29, 2010}}</ref>

<ref name="NYTimesJune17-2006">{{cite news |first=Kate |last=Hafner |title=Growing Wikipedia Refines Its 'Anyone Can Edit' Policy |url=http://www.nytimes.com/2006/06/17/technology/17wiki.html?scp=8&sq=wikipedia&st=cse |work=The New York Times |date=June 17, 2006 |accessdate=July 12, 2009}}</ref>

<ref name="iTWireJune18-2006">{{cite news |first=Stuart |last=Corner |title=What's all the fuss about Wikipedia? |url=http://www.itwire.com/content/view/4666/127/ |publisher=iT Wire |date=June 18, 2006 |accessdate=March 25, 2007}}</ref>

<ref name="David_Mehegan">{{cite news |first=David |last=Mehegan |title=Many contributors, common cause |url=http://www.boston.com/business/technology/articles/2006/02/13/many_contributors_common_cause/ |work=Boston Globe |date=February 13, 2006 |accessdate=March 25, 2007}}</ref>

<ref name="user identification">{{cite web|title=The Authority of Wikipedia|url=http://www.public.iastate.edu/~goodwin/pubs/goodwinwikipedia.pdf|author=Jean Goodwin|year=2009|quote=Wikipedia's commitment to anonymity/pseudonymity thus imposes a sort of epistemic agnosticism on its readers|accessdate=January 31, 2011}}</ref>

<ref name="ListOfWikipedias">{{cite web| url = https://en.wikipedia.org/wiki/Special:Statistics | title = Statistics | publisher = [[English Wikipedia]] | accessdate=June 21, 2008 }}</ref>

<ref name="servers">{{cite web|url=http://wikitech.wikimedia.org/view/Server_roles|title=Server roles at wikitech.wikimedia.org|accessdate=December 8, 2009}}</ref>

<ref name="AlexaTop500">{{cite web|url=http://www.alexa.com/site/ds/top_sites?ts_mode=global&lang=none |title=Top 500 |publisher=[[Alexa Internet|Alexa]] |accessdate=October 13, 2009 }}</ref>

<ref name="WP_court_source">{{cite journal|last=Arias |first=Martha L. |date=January 29, 2007 |url=http://www.ibls.com/internet_law_news_portal_view.aspx?s=latestnews&id=1668 |title=Wikipedia: The Free Online Encyclopedia and its Use as Court Source |journal=Internet Business Law Services |accessdate=December 26, 2008}} (The name "''World Intellectual Property Office''" should however read "''World Intellectual Property Organization''" in this source.)</ref>

<ref name=twsY23>{{cite news |author= Lexington |title= Classlessness in America: The uses and abuses of an enduring myth |work=The Economist |quote= Socialist Labour Party of America ... Though it can trace its history as far back as 1876, when it was known as the Workingmen’s Party, no less an authority than Wikipedia pronounces it "moribund". |date=September 24, 2011 |url= http://www.economist.com/node/21530100 |accessdate=September 27, 2011 }}</ref>

<ref name="Domesday Project">[http://www.domesday1986.com/ Website discussing the emulator of the Domesday Project User Interface] for the data from the Community Disc (contributions from the general public); the site is currently out of action following the death of its creator</ref>

<ref name="OurProjects">[http://wikimediafoundation.org/wiki/Our_projects "Our projects"], [[Wikimedia Foundation]]. Retrieved January 24, 2007.</ref>

<ref name="Orlowski18">{{cite news |first=Andrew |last=Orlowski |authorlink=Andrew Orlowski |url=http://www.theregister.co.uk/2006/09/18/sanger_forks_wikipedia/ |title=Wikipedia founder forks Wikipedia, More experts, less fiddling? |work=The Register |date=September 18, 2006 |quote=Larry Sanger describes the Citizendium project as a "progressive or gradual fork," with the major difference that experts have the final say over edits.|accessdate=June 27, 2007 }}&nbsp;– Andrew Orlowski.</ref>

<ref name="JayLyman">{{cite news |first=Jay |last=Lyman |url=http://www.crmbuyer.com/story/53137.html |title=Wikipedia Co-Founder Planning New Expert-Authored Site |publisher=LinuxInsider |date=September 20, 2006 |accessdate=June 27, 2007}}</ref>

<ref name=anyone>{{cite news|url=http://www.huffingtonpost.co.uk/2011/08/29/wikipedias-jimmy-wales-sp_n_941239.html|title = Wikipedia's Jimmy Wales Speaks Out On China And Internet Freedom|work=Huffington Post|quote=Currently Wikipedia, Facebook and Twitter remain blocked in China|accessdate=September 24, 2011}}</ref>

<ref name="AlexaStats">{{cite web|url=http://www.alexa.com/data/details/traffic_details/wikipedia.org?range=5y&size=large&y=t|title = Five-year Traffic Statistics for Wikipedia.org|publisher=[[Alexa Internet]]|accessdate=June 18, 2013 }}</ref>

<ref name=Tancer>{{cite news|url=http://www.time.com/time/business/article/0,8599,1595184,00.html|title=Look Who's Using Wikipedia|author=Bill Tancer|date=May 1, 2007|work=[[Time (magazine)|Time]]|quote=The sheer volume of content […] is partly responsible for the site's dominance as an online reference. When compared to the top 3,200 educational reference sites in the U.S., Wikipedia is No. 1, capturing 24.3% of all visits to the category|accessdate=December 1, 2007}}. [[Cf.|{{lang|la|{{dabbr|Cf|Confer}}|nocat=true}}]] Bill Tancer (Global Manager, Hitwise), [http://weblogs.hitwise.com/bill-tancer/2007/03/wikipedia_search_and_school_ho.html "Wikipedia, Search and School Homework"], ''[[Hitwise]]'', March 1, 2007.</ref>

<ref name=Woodson>{{cite news|url=http://www.reuters.com/article/internetNews/idUSN0819429120070708 |title=Wikipedia remains go-to site for online news |date=July 8, 2007|author=Alex Woodson |agency=Reuters |quote=Online encyclopedia Wikipedia has added about 20 million unique monthly visitors in the past year, making it the top online news and information destination, according to Nielsen//NetRatings.|accessdate=December 16, 2007}}</ref>

<ref name="365M">[http://upload.wikimedia.org/wikipedia/meta/3/3a/TED2010%2C_Stuart_West_full_presentation_updated_with_January_data.pdf ''Wikipedia's Evolving Impact''], by Stuart West, slideshow presentation at TED2010.</ref>

<ref name=TCrunch>{{cite web |url=http://techcrunch.com/2011/02/05/wikipedia-affiliate-links/ |title=Please Read: A Personal Appeal TO Wikipedia Founder Jimmy Wales |last=Walk |first=Hunter |publisher=TechCrunch |date=February 5, 2011 |accessdate=September 24, 2011 }}</ref>

}}

=== Further reading ===
==== Academic studies ====
{{main|Academic studies about Wikipedia}}
{{Refbegin}}
* Jensen, Richard. "Military History on the Electronic Frontier: Wikipedia Fights the War of 1812", ''The Journal of Military History'' 76#4 (October 2012): 523–556; [http://www.americanhistoryprojects.com/downloads/JMH1812.PDF online version].
* {{cite journal|url=http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0030091 |title=Circadian Patterns of Wikipedia Editorial Activity: A Demographic Analysis |first=Taha |last=Yasseri |year=2012 |journal=PLoS ONE |volume=7 |coauthor=Robert Sumi and János Kertész |issue=1|doi=10.1371/journal.pone.0030091|editor1-last=Szolnoki|editor1-first=Attila|pages=e30091|pmid=22272279|pmc=3260192|arxiv = 1109.1746 |bibcode = 2012PLoSO...7E0091Y }}
* {{cite journal|url=http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1458162## |title=Wikipedia's Labor Squeeze and its Consequences |first=Eric |last=Goldman |year=2010 |journal=Journal of Telecommunications and High Technology Law |volume=8}} ([http://blog.ericgoldman.org/archives/2010/02/catching_up_wit.htm A blog post by the author.])
* {{cite journal|first=Finn|last=Nielsen|url=http://www.firstmonday.org/issues/issue12_8/nielsen/index.html|title=Scientific Citations in Wikipedia|journal=[[First Monday (journal)|First Monday]]|volume=12 |issue=8|month=August|year=2007|accessdate=February 22, 2008|doi=10.5210/fm.v12i8.1997}}
* {{cite journal|last=Pfeil|first=Ulrike|coauthors=Panayiotis Zaphiris and Chee Siang Ang|title=Cultural Differences in Collaborative Authoring of Wikipedia|journal=Journal of Computer-Mediated Communication|year=2006|volume=12|issue=1| page=88|url=http://jcmc.indiana.edu./vol12/issue1/pfeil.html |doi=10.1111/j.1083-6101.2006.00316.x|accessdate=December 26, 2008}}
* Priedhorsky, Reid, Jilin Chen, Shyong (Tony) K. Lam, Katherine Panciera, Loren Terveen, and John Riedl. [http://portal.acm.org/citation.cfm?doid=1316624.1316663 "Creating, Destroying, and Restoring Value in Wikipedia"]. Proc. GROUP 2007; DOI: 1316624.131663.
* {{cite conference
| first = Joseph
| last = Reagle
| title = Do as I Do: Authorial Leadership in Wikipedia
| booktitle = WikiSym '07: Proceedings of the 2007 International Symposium on Wikis
| publisher = ACM
| location = Montreal, Canada
| year = 2007
| url = http://reagle.org/joseph/2007/10/Wikipedia-Authorial-Leadership.pdf
| accessdate=December 26, 2008}}
* [[Roy Rosenzweig|Rosenzweig, Roy]]. [http://chnm.gmu.edu/resources/essays/d/42 Can History be Open Source? Wikipedia and the Future of the Past]. (Originally published in ''[[The Journal of American History]]'' 93.1 (June 2006): 117–46.)
* {{cite journal|url=http://www.firstmonday.org/issues/issue12_4/wilkinson/index.html |title=Assessing the Value of Cooperation in Wikipedia |first=Dennis M.|last=Wilkinson |coauthor=Bernardo A. Huberman|journal=First Monday|volume=12|issue=4|month=April|year=2007| accessdate=February 22, 2008|doi=10.5210/fm.v12i4.1763 }}
* {{cite journal|url=http://abs.sagepub.com/content/57/5/664 |title=The Rise and Decline of an Open Collaboration Community |journal=American Behavioral Scientist |author=Aaron Halfaker, R. Stuart Geiger, Jonathan T. Morgan, John Riedl|accessdate=August 30, 2012|doi=10.1177/0002764212469365|year=2012|volume=57|issue=5|page=664}}
{{Refend}}

==== Books ====
{{main|List of books about Wikipedia}}
{{Refbegin}}
* {{cite book|first1=Phoebe|last1= Ayers|first2= Charles|last2= Matthews|first3=Ben|last3= Yates|title=[[How Wikipedia Works]]: And How You Can Be a Part of It |publisher=No Starch Press |location=San Francisco |month=September |year=2008 |isbn=978-1-59327-176-3 }}
* {{cite book|last=Broughton |first=John|title=[[Wikipedia – The Missing Manual]] |publisher=O'Reilly Media |year=2008 |isbn=0-596-51516-2 }} (See book review by Baker, as listed hereafter.)
* {{cite book| last = Broughton | first = John | title = Wikipedia Reader's Guide | publisher = Pogue Press | location = Sebastopol | year = 2008 | isbn = 0-596-52174-X }}
* {{cite book| last = Dalby | first = Andrew | authorlink = Andrew Dalby |title = [[The World and Wikipedia|The World and Wikipedia: How We are Editing Reality]] | publisher = Siduri | year = 2009 | isbn = 978-0-9562052-0-9 }}
* {{cite book|last=Keen|first=Andrew | title=[[The Cult of the Amateur]] | publisher=Doubleday/Currency | year=2007 | isbn=978-0-385-52080-5 | authorlink=Andrew Keen}} (Substantial criticisms of Wikipedia and other web 2.0 projects.)
** Listen to:
*** {{cite web|last=Keen |first=Andrew |url=http://www.npr.org/templates/story/story.php?storyId=11131872 |title=Does the Internet Undermine Culture? |publisher=National Public Radio, USA |date=June 16, 2007 }} The NPR interview with A. Keen, Weekend Edition Saturday, June 16, 2007.
* {{cite book| last = Lih | first = Andrew | authorlink = Andrew Lih | title = [[The Wikipedia Revolution|The Wikipedia Revolution: How a Bunch of Nobodies Created the World's Greatest Encyclopedia]] | publisher = Hyperion | location = New York | year = 2009 | isbn = 978-1-4013-0371-6 }}
* {{cite book|last=O'Sullivan|first=Dan|title=Wikipedia: a new community of practice?|url=http://books.google.com/books?id=htu8A-m_Y4EC|date=September 24, 2009|publisher=Ashgate Publishing|isbn=978-0-7546-7433-7}}
* [[Sheizaf Rafaeli]] & Yaron Ariel (2008). "Online motivational factors: Incentives for participation and contribution in Wikipedia." In {{cite book |author=Barak, A. |title=Psychological aspects of cyberspace: Theory, research, applications |pages=243–267 |location=Cambridge, UK |publisher=[[Cambridge University Press]]}}
* {{cite book| last = Reagle | first = Joseph Michael Jr. | title = Good Faith Collaboration: The Culture of Wikipedia | publisher = the MIT Press | location = Cambridge, Massachusetts, USA | year = 2010 | isbn = 978-0-262-01447-2 |url = http://reagle.org/joseph/2010/gfc/}}
{{Refend}}

==== Book reviews and other articles ====
{{Refbegin}}
* [[Nicholson Baker|Baker, Nicholson]]. [http://www.nybooks.com/articles/21131 "The Charms of Wikipedia"]. ''[[The New York Review of Books]]'', March 20, 2008. Retrieved December 17, 2008. (Book rev. of ''The Missing Manual'', by John Broughton, as listed previously.)
* [[L. Gordon Crovitz|Crovitz, L. Gordon]]. [http://online.wsj.com/article/SB123897399273491031.html "Wikipedia's Old-Fashioned Revolution: The online encyclopedia is fast becoming the best."] (Originally published in [[The Wall Street Journal|''Wall Street Journal'']] online&nbsp;– April 6, 2009.)
{{Refend}}

'''Learning resources'''
{{Refbegin}}
* [[v:wikipedia#Learning resources|Wikiversity list of learning resources]]. (Includes related courses, [[Web conferencing|Web-based seminars]], slides, lecture notes, text books, quizzes, glossaries, etc.)
{{Refend}}

'''Other media coverage'''
{{see also|List of films about Wikipedia}}
{{Refbegin}}
* {{cite news|last=Balke|first=Jeff|url=http://blogs.chron.com/brokenrecord/2008/03/for_music_fans_wikipedia_myspa.html|title=For Music Fans: Wikipedia; MySpace|work=[[Houston Chronicle]] (blog)|date=2008-03|accessdate=December 17, 2008}}
* {{cite news|url=http://www.nytimes.com/2007/07/01/magazine/01WIKIPEDIA-t.html?_r=1&ref=magazine&oref=slogin |title=All the News That's Fit to Print Out|first=Jonathan |last=Dee|work=The New York Times Magazine |date=July 1, 2007|accessdate=February 22, 2008}}
* {{cite news|first=Jim |last=Giles|title=Wikipedia 2.0&nbsp;– Now with Added Trust |url=http://www.newscientist.com/article/mg19526226.200|date=September 20, 2007|work=[[New Scientist]] |accessdate=January 14, 2008}}
* {{cite news|first=Mike |last=Miliard|title=Wikipedia Rules |url=http://thephoenix.com/Boston/Life/52864-Wikipedia-rules/|publisher=[[The Phoenix (newspaper)|The Phoenix]]|date=December 2, 2007|accessdate=February 22, 2008}}
* {{cite news|first=Marshall|last=Poe|authorlink=Marshall Poe|url=http://www.theatlantic.com/doc/200609/wikipedia|title=The Hive|work=[[The Atlantic|The Atlantic Monthly]]|date=2006-09|accessdate=March 22, 2008}}
* {{cite news|first=Michael S.|last=Rosenwald|url=http://www.washingtonpost.com/wp-dyn/content/article/2009/10/22/AR2009102204715.html?hpid=topnews |title=Gatekeeper of D.C.'s entry: Road to city's Wikipedia page goes through a DuPont Circle bedroom|date=October 23, 2009|work=The Washington Post|accessdate=October 22, 2009}}
* {{cite news|first=David|last=Runciman|url=http://www.lrb.co.uk/v31/n10/runc01_.html |title=Like Boiling a Frog|date=May 28, 2009|work=London Review of Books|accessdate=June 3, 2009}}
* {{cite news|first=Chris|last=Taylor|url=http://www.time.com/time/magazine/article/0,9171,1066904-1,00.html|title=It's a Wiki, Wiki World|date=May 29, 2005|work=[[Time (magazine)|Time]]|accessdate=February 22, 2008}}
* {{cite news|url=http://www.economist.com/science/tq/displaystory.cfm?story_id=11484062 |title=Technological Quarterly: Brain Scan: The Free-knowledge Fundamentalist|work=[[The Economist|The Economist Web]] and [[Magazine|Print]]|date=June 5, 2008|accessdate=June 5, 2008|quote=Jimmy Wales changed the world with Wikipedia, the hugely popular online encyclopedia that anyone can edit. What will he do next?}}
* [http://www.independent.co.uk/life-style/gadgets-and-tech/features/is-wikipedia-cracking-up-1543527.html ''Is Wikipedia Cracking Up?'' ''The Independent'', February 3, 2009.]
{{Refend}}

== External links ==
{{Sister project links|Wikipedia|voy=no|d=Q52}}

* {{official website|www.wikipedia.org|mobile=mobile.wikipedia.org}}&nbsp;– multilingual portal (contains links to all language editions of the project)
* {{Twitter|Wikipedia}}
* {{Facebook|Wikipedia}}
* {{Dmoz|Computers/Open_Source/Open_Content/Encyclopedias/Wikipedia}}
* [[tools:~johang/wikitrends/english-most-visited-today.html|Wikitrends: most visited Wikipedia articles]]
* {{Guardiantopic|technology/wikipedia}}
* [http://topics.nytimes.com/top/news/business/companies/wikipedia/index.html Wikipedia] topic page at ''[[The New York Times]]''
* [http://www.ted.com/index.php/talks/jimmy_wales_on_the_birth_of_wikipedia.html Video of TED talk by Jimmy Wales on the birth of Wikipedia]
* [http://www.econtalk.org/archives/2009/03/wales_on_wikipe.html Audio of interview with Jimmy Wales about Wikipedia in general] on the [[EconTalk]] podcast
* [http://www.stanford.edu/class/ee380/Abstracts/020116.html Wikipedia and why it matters]&nbsp;– Larry Sanger's 2002 talk at [[Stanford University]]; [http://stanford-online.stanford.edu/courses/ee380/020116-ee380-100.asx video archive] and [[meta:Wikipedia and why it matters|transcript of the talk]]
* {{youtube|id=cqOHbihYbhE|title="Intelligence in Wikipedia" Google TechTalk}}, describing an intelligence project utilizing Wikipedia, and how Wikipedia articles could be auto-generated from web content
* [http://wikipapers.referata.com WikiPapers] – compilation of conference papers, journal articles, theses, books, datasets and tools about Wikipedia and wikis

{{Wikipedia}}
{{Wikimedia Foundation}}
{{Wikipedias}}

{{Good article}}

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