Wikipedia:Manual of Style/Linking
 | This guideline is a part of the English Wikipedia's Manual of Style. It is a generally accepted standard that editors should attempt to follow, though it is best treated with common sense, and occasional exceptions may apply. Any substantive edit to this page should reflect consensus. When in doubt, discuss first on the talk page. |
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Internal links
The use of links to other Wikipedia articles, for example, [[Ant]], is encouraged. Use the links for all words and terms that are relevant to the article.
The purpose of internal links is to allow readers to easily and conveniently follow their curiosity or research to other articles. These links should be included where it is most likely that a reader would want to follow them elsewhere; for example, in article introductions, the beginnings of new sections, table cells, and image captions. Generally, where it is likely that a reader may wish to read about another topic, the reader should not have to hunt for a link elsewhere in the page.
As a general rule, do not put links in the title; however, this may be acceptable with complex titles or verbose leads, such as those concerning multiple concepts.
Dead red internal links: not abominations, but rather how and where Wikipedia grows
In a nutshell: A red link, or nonworking internal hyperlink, is not an emergency and it is not a promise.
Terms which are given link parentheses, but do not presently link to a wiki, appear in the default user settings, in red. This may be an unfortunate choice of color, since red to many people signals danger, or something not working which needs immediate fixing. This is not necessarily the case with non-working internal (red) links, however. A non-working link does not mean that something is wrong in Wikipedia, and despite the color, it actually is not demanding to be immediately fixed, either by removing the link brackets, or by creating a page which expands upon it. These things may be done later. Nature will not cry out, if these things are not done immediately. In fact, a good healthy wiki article will probably have a certain amount of nonworking links, so long as wikipedia grows properly. The personal reader settings can be changed by the user so these links show in any other color.
Nonworking internal links are often perfectly normal things, like twig buds on a plant. They are markers for places where an editor has essentially commented, using brackets, that he or she would like to see a Wiki on this topic, but found that it didn't exist. That's okay. If the editor didn't have the immediate time or knowledge to expand upon a term, the mere marking of interest may stimulate another editor with more time or knowledge or initiative, to begin work on the article at some later date. This is a good thing. In the meantime, it is often best if the non-working link is left alone. There is nothing wrong with such links. Editors who are offended by the violent red word color are encouraged to go back to their user settings page, and change it for their own reader, so that they themselves can read articles in peace, and thus leave this variety of links in peace. The dead internal link is important, and needs to remain, if Wikipedia is to grow naturally fastest, and in the best way (which is to say, in the direction of writing new articles about undefined terms-of-interest).
Editors may notice that some nonworking internal links really are pathological. For example, they may link to words that don't need links because they aren't likely to ever be the topics of Wikipedia articles. But note the actually working links to simple words in the preceding sentence-- this matter is not always easy to figure out without a test-try to see where the link goes. In such cases, though, it's perfectly fine to remove the brackets if they don't help and are never likely to, in the particular instance you're looking at. Also, editors may notice that a link is not working because somebody has mistakenly included the plural s inside the bracket, or because the word is misspelled, or other obvious technical problem of this sort. Again, these can and should be fixed in the obvious ways, creating a working link (for example, move the plural s outside the link bracket).
Finally, an editor who knows enough about a nonworking link topic to write a stub on it, can do so by clicking on it, thus starting the (new) Wiki page on that topic. If the editor has time, this is always preferable to removing the brackets on a non-working link, if the link is to a word which is likely to ever be worth an article or stub. Probably the best of all solutions involves figuring out that the non-working link is actually linked in another way under another term, which is to say, a variant of a term which already has a wiki, so that the link can either be changed to the existing wiki, or a redirect page can be created (creating a redirect is the better option if the non-working term is a very common but not technically correct one, for example transistor radio battery vs. PP3 battery)
What a dead link is not. What a nonworking internal hyperlink is not, is a promise, or a deadline. So, it need not be treated as an promisory note, or a bill from the tax board. The person who made the dead link is under no moral obligation to come back and fix things by expanding it into a stub or article, even if they once intended to. And you, the editor, are also under no obligation to watch a non-working link for some period of time, to make sure that somebody eventually "attends" to it, as though it were a parking ticket. Again, nonworking internal links are not wet babies. Unless the nonworking link is a pathological link (see above) there's no particular hurry for anybody to attend to it. And if the color of it is distracting you as a reader, you can change it for your own browser/reader, as noted. But please leave the link itself alone. It is actually serving a purpose and function, like a bud. A legitimate dead link is a request, but only a mild one. If you can't fill it, what it needs most from you, the editor, is not to be bothered by you, until somebody else can expand the connection into a Wiki.
Overlinking and underlinking: what's the best ratio?
On the other hand, do not make too many links. An article may be considered overlinked if any of the following is true:
- More than 10% of the words are contained in links;
- More than 10% of the links are to articles that don't exist; or
- Low added-value items are linked without reason — such as, 1995, 1980s, and 20th century.
- A link for any single term is excessively repeated in the same article, as in the example of overlinking which follows: "Excessive" is more than once for the same term, in a line or a paragraph, because in this case one or more duplicate links will almost certainly then appear needlessly on the viewer's screen. Remember, the purpose of links is to direct the reader to a new spot at the point(s) where the reader is most likely to take a temporary detour due to needing more information;
- However, note that duplicating an important link distant from a previous occurrence in an article, may well be appropriate (but see the exception about dates, below). Good places for link duplication are often the first time the term occurs in each article subsection. Thus, if an important technical term appears many times in a long article, but is only linked once at the very beginning of the article, it may actually be underlinked. But take care in fixing such problems. If an editor finds themselves "reflexively" linking a term without having a good look around the entire article, it is often time to stop and reconsider.
These guidelines also apply to tables, considered by themselves.
Form
Links that follow the Wikipedia naming conventions are much more likely to lead to existing articles. When there is not yet an article about that subject, good links will make the creation of a correctly named article much easier for later writers.
It is possible to link words that are not exactly the same as the linked article title — for example, [[English language|English]]. However, make sure that it is still clear what the link refers to without having to follow the link.
When forming plurals, do so thus: [[language]]s. This is clearer to read in wiki form than [[language|languages]] — and easier to type. This syntax is also applicable to adjective constructs such as [[Asia]]n and the like. Hyphens and apostrophes must be included in the link to show as part of it for example [[Jane's Fighting Ships|Jane's]] or [[truant|playing-the-hop]]. Keeping possessive apostrophes inside the link, where possible, makes for more readable text and source.
Context
As the World Wide Web Consortium says, "Don't say 'click here'; not everyone will be clicking". Link an existing word or phrase in context.
While editing, use preview to check a link, and follow it by opening the page in another window. If that title doesn't seem to exist, do a quick search to find out whether that is really the case. The article may have a differently worded title, or the subject may be included in a separate section of an existing article.
Links should use the most precise target that arises in the context, even where that is merely a simple redirect to a less specific page title. Don't use a piped link to avoid otherwise legitimate redirect targets that fit well within the scope of the text. This assists in determining when a significant number of references to redirected links warrant more detailed articles. For example, link to "V8 engine" rather than "V8 engine".
Automated processes should not replace or pipe links to redirects. Instead, the link should always be examined in context. (For more information, see Wikipedia:Disambiguation, Wikipedia:Redirect#Don't fix links to redirects that aren't broken, and Wikipedia:Redirects with possibilities.)
Dates and numbers
Where a date contains day, month, and year — [[25 March]], [[2004]] — or day and month — [[February 10]] — a link will permit the date preferences of the reader to operate. Day, month, and year must all be linked for the preference to work fully.
Preferences and, in some cases, editorial freedom regarding the linking of dates are discussed in Wikipedia:Manual of Style (dates and numbers)#Dates.
Capitalisation
There is currently no rule prescribing whether one should write "See also Train" or "See also train" (and similar with a bulleted list), but in the case of multiple links, be consistent. Note that linking does not force use of a capital letter, if you don't desire one in the interest of readability.
Quotation
Words in quotations should not be linked for context. The text should remain in the same form and with the same emphasis as it did in the source. This is especially true for linking dates which, if linked, are changed according to readers’ date preferences.
External links
Wikipedia is not a link collection and an article with only links is actively discouraged.
Syntax
The syntax for referencing a URL is simple. Just enclose it in single brackets:
[URL link title after space]
The URL must begin with http:// or another common protocol, such as ftp:// or news://.
In addition, putting URLs in plain text with no markup automatically produces a link, for example http://en.wikipedia.org/. However, this feature may disappear in a future release. Therefore, in cases where you wish to display the URL because it is intrinsically valuable information, it is better to use the short form of the URL (host name) as the optional text: [http://en.wikipedia.org/ en.wikipedia.org] produces en.wikipedia.org.
Link titles
You should not add a descriptive title to an embedded HTML link within an article. Instead, when giving an embedded link as a source within an article, simply enclose the URL in square brackets, like this. [1] However, you should add a descriptive title when an external link is offered in the References, Further reading, or External links section. This is done by supplying descriptive text after the URL, separated by a space and enclosing it all in square brackets.
For example, to add a title to a bare URL such as http://en.wikipedia.org/ (this is rendered as "http://en.wikipedia.org/"), use the following syntax: [http://en.wikipedia.org/ an open-content encyclopedia] (this is rendered as "an open-content encyclopedia").
Generally, URLs are ugly and uninformative; it is better for a meaningful title to be displayed rather than the URL itself. For example, "European Space Agency website" is much more reader-friendly than "http://www.esa.int/export/esaCP/index.html". There may be exceptions where the url is well known or is the company name. In this case, putting both the url and a valid title will be more informative, for example, "European Space Agency website, www.esa.int".
If the URL is displayed, make it as simple as possible; for example, if the index.html is superfluous, remove it (but be sure to check in preview mode first).
The "printable version" of a page displays all URLs in full, including those given a title, so no information is lost.
URLs as embedded (numbered) links
Without the optional text, external references appear as automatically numbered links: For example,
[http://en.wikipedia.org/]
is displayed like this:
When an embedded HTML link is used to provide an inline source in an article, a numbered link should be used after the punctuation, like this, [3] with a full citation given in the References section. See Wikipedia:Cite sources and Wikipedia:Verifiability for more information.
When placed in the References and External links sections, these links should be expanded with link text, and preferably a full citation, including the name of the article, the author, the journal or newspaper the article appeared in, the date it was published, and the date retrieved.
Position in article
Embedded links are positioned after the sentence or paragraph they are being used as a source for, and after the punctuation, like this. [4]
A full citation should then be added to the References section. Links not used as sources can be listed in the External links section:
==External links==*[http://*[http://
As with other top-level headers, two equal signs should be used to markup the external links header (see Headings elsewhere in the article).
If there is a dispute on the position an embedded link, consider organizing alphabetically.
See Wikipedia:Citing_sources#Embedded_HTML_links for how to format these, and Wikipedia:Verifiability, which is policy.
Foreign-language sites
Since this is the English Wikipedia, webpages in English are highly preferred. Linking to non-English pages may still be useful for readers in some cases:
- when the website is the subject of the article
- when linking to pages with maps, diagrams, photos, tables; explain the key terms with the link, so that people who do not know the language can still interpret them
- when the webpage contains key information found on no English-language site and is used as a citation
In such cases indicate what language the site is in. For example:
You can also indicate the language by putting a language icon after the link. This is done using Template:Languageicon by typing {{Languageicon|<language code>|<language name>}}. Alternatively, you may type {{xx icon}}, where xx is the language code. See Category:Language icons for a list of these templates and the list of ISO 639 codes.
File type
If the link is not to an HTML file, identify the file type. If a browser plugin is required to view to the file, mention that as well.
File size
If the link is to a large file (in the case of html, including the images) a note about that is useful. Someone with a slow connection may decide not to use it.