Wikipedia:Manual of Style/Linking

Linking is one of the most important features of Wikipedia. It binds the project together into an interconnected whole, and provides instant pathways to locations both within and outside the project that are likely to increase our readers' understanding of the topic at hand. This page contains guidelines as to when links should and should not be used, and how to format them. Detailed information about the syntax used to create links can be found at Help:Link.

For the special rules on linking applicable to disambiguation pages, see the disambiguation style guide.

General principles

Items in Wikipedia articles can be linked to other Wikipedia articles which are likely to add significantly to readers' understanding of the topic. As explained in more detail at Help:Links#Wikilinks, this can be done directly ("[[Ant]]", which results in "Ant"), or through a piped link ("[[Ant|five new species]]", which results in "five new species" in the text, but still links to the article "Ant").

Internal links add to the cohesion and utility of Wikipedia by allowing readers to deepen their understanding of a topic by conveniently accessing other articles. These links should be included where it is most likely that readers might want to use them; for example, in article leads, the beginnings of new sections, table cells, and image captions. Wikipedia's articles function as nodes in a hypertext system—making links between them helps to build a web of information which readers can navigate effectively.

The following general principles apply to internal linking:

• Do not place links in section headings. (It may be useful to place a {{main}} or {{seealso}} template immediately after the heading.)
• Do not place links in the bold reiteration of the title in the article's lead sentence.
• Avoid linking to a page that redirects back to the page the link is on.
• Generally avoid linking items within quotations; instead, place links in the surrounding text of the article wherever possible.
• If possible, avoid placing two links next to each other in the text so they look like a single link (such as internal links).
• Link to a more specific topic if it has its own article; for example, link to "the flag of Tokelau" instead of "the flag of Tokelau"; link to a section within an article if that brings the reader immediately to the information of specific relevance.
• Link only the first occurrence of an item. A link that had last appeared much earlier in the article may be repeated, but generally not in the same section. (Table entries are an exception to this; each row of a table should be able to stand on its own.)
• Think carefully before you remove a link altogether—what may seem like an irrelevant link to you may be useful to other readers.
• Do not be afraid to create links to potential articles that do not yet exist (see Red links below).
• If you feel that a certain link does not belong in the body of the text, consider moving it to a "See also" section at the bottom of the article. (Remember that links can also be useful when applying the "What links here" feature from the target page.)

Overlinking and underlinking

An article is said to be underlinked if subjects are not linked that are necessary to the understanding of the article or its context. However, overlinking is also something to be avoided. A high density of irrelevant links makes it harder for the reader to identify and follow those links which are likely to be of value. Provide links that aid navigation and understanding; avoid cluttering the page with obvious, redundant and useless links.

What generally should not be linked

It is generally not appropriate to link:

• plain English words.
• terms whose meaning (as relevant to the context of the article) would be understood by almost all readers.
• items that would be familiar to most readers, such as the names of major geographic features and locations, historical events, religions, languages, common professions and common units of measurement (particularly if a conversion is provided), except if they are particularly relevant to the topic of the article.
• dates (but see Chronological items below).

What generally should be linked

In general, do create links to:

• relevant connections to the subject of another article that will help readers to understand the current article more fully (see the example below). This can include people, events and topics that already have an article or that clearly deserve one, as long as the link is relevant to the article in question.
• articles with relevant information, through references (Example: "see Fourier series for relevant background"). Linking items in a list of examples makes them easier to reference as well.
• technical terms, unless they are fully defined in the article and do not have their own separate article. Sometimes the most appropriate link is an interwiki link to Wiktionary. Consider instead defining technical terms immediately, if this can be worked into the sentence neatly and concisely.
• explicit articles when word usage may be confusing to a non-native speaker (or users of other varieties of English). If the word would not be translated in context with an ordinary foreign-language dictionary, consider linking to an article or Wiktionary entry to help foreign language readers, especially translators. Check the link for disambiguation, and link to the specific item.
• articles of geographic places that are likely to be unfamiliar to readers or that in the context may be confused with places that have a similar or identical name.

Link density

Aim for a consistent link density. Do not link eight words in one sentence and then none in the rest of the article. The introduction of the article may require modification of this rule. For general-interest articles, where the links are of the "see also" or "for more information" type, it may be better to not link in the summary, deferring the link until the term is defined later in the article. Numerous links in the summary of an article may cause users to jump elsewhere rather than read the whole summary. For technical articles, where terms in the summary may be uncommon or unusual, and linking is necessary to facilitate understanding, it is permissible and may even be necessary to have a high link density in the introduction.

Example

In the article on supply and demand:

• almost certainly link microeconomic theory and general equilibrium as these are technical terms that many readers are unlikely to understand at first sight;
• consider linking price and goods only if these common words have technical dimensions that are specifically relevant to the topic (a section-link is generally preferable in this case);
• not link to the "United States", because that is a very large article with no explicit connection to supply and demand.
• definitely not link "potato", because it is a common term with no particular relationship to the article on supply and demand, beyond its arbitrary use as an example of traded goods in that article.

Chronological items

Items such as days, years, decades and centuries should generally not be linked unless they are likely to deepen readers' understanding of the topic. Articles about other chronological items or related topics are an exception to this guideline.

Links to articles on a topic in a specific chronological period, such as 1441 in art, 1982 in film, and 18th century in the United States, may add significantly to readers' understanding of the current topic. One such link per article is enough to serve as a gateway for readers to access sibling articles for other years (1983 in film and so on); multiple links throughout an article are unnecessary. Year-in-X links should generally be kept explicit, so that readers can see where they lead, but they may be piped to look like plain year links – for example [[1997 in South African sport|1997]] – in some tables, infoboxes or lists where compact presentation and uniform display are important.

Piped links

It is possible to link words that are not exactly the same as the linked article title—for example, [[Henry II of England|Henry II]]. However, make sure that it is still clear what the link refers to without having to follow the link.

• Plurals and possessives. When forming plurals, do so thus: [[greengage]]s. This is clearer to read in wiki form than [[greengage|greengages]]—and easier to type. This syntax is also applicable to adjective constructs such as [[Moldova]]n and the like. Hyphens and apostrophes must be included in the link to show as part of the same word. 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, though either form is acceptable for possessive forms of links such as [[George Washington]]'s or [[George Washington|George Washington's]].

• Case sensitivity. Links are not sensitive to initial capitalization, so there is no need to use piping where the only difference between the text and the target is the case of the initial letter. However, links are case-sensitive for all but the initial character.

• Piping and redirects. Do not use a piped link where it is possible to use a redirected term that fits well within the scope of the text. This assists in determining when a significant number of references to redirected links warrant more detailed articles. Automated processes should not convert links to redirects into piped links; the link should always be examined in context. For more information, see Do not "fix" links to redirects that are not broken and Redirects with possibilities.

• Intuitiveness. Keep piped links as intuitive as possible. Do not use them to create "easter egg links", that require the reader to follow them to understand the term. Wikipedia's articles are sometimes read in hard copy, where the option of following a link is not available. For example, do not write this:

... and by mid-century the puns and sexual humor were back to stay (with a few [[Thomas Bowdler|exceptions]]).

The readers will not see the hidden reference to Thomas Bowdler unless they click on or hover over the piped exceptions link; in hard copy, the reference to Bowdler is completely lost. Instead, reference the article with an explicit "see also" or by rephrasing:

... and by mid-century the puns and sexual humor were back to stay (with only a few exceptions; see [[Thomas Bowdler]]).

... and by mid-century the puns and sexual humor were back to stay, aside from a few exceptions such as the writings of [[Thomas Bowdler]].

Similarly, use:

After an earlier disaster (see Bombay Explosion (1944)),... or

After an earlier disaster (Bombay Explosion (1944)),... or

After the earlier explosion in Bombay,...

rather than:

After an earlier disaster,...

Piped links should never be used to introduce tendentious subtext, as in "He denied the [[rumor|allegation]]."

Linking to sections of articles

Linking to particular sections of articles can be useful, since it can take the reader immediately to the information that is most focused on the original topic. The format for a subsection link is [[Article#Section|name of link]]. For example, to link to the "Culture" subsection of the Oman article, type [[Oman#Culture|culture of Oman]]. When naming a piped link, think about what the reader will believe the link is about; in this example, the piped section-link should not be named "Oman", because the reader will think that link goes to the general article on Oman.

Although it is common to used piped links when linking to sections, e.g.:

[[Baden-Württemberg#Geography|Geography of Baden-Württemberg]]

(Geography of Baden-Württemberg)

this often becomes unwieldy in the main prose, so it may be preferable to create and link to a redirect, e.g.:

[[Geography of Baden-Württemberg]]

(Geography of Baden-Württemberg)

which points to a section within the main Baden-Württemberg article, and may also become a separate article in the future (see also WP:REDIRECT#NOTBROKEN). In addition, Special:Whatlinkshere currently provides no way to determine which pages link to which section(s) of a given article, so creating redirects offers a way to filter incoming links and identify related articles.

Red links

Main page: Wikipedia:Red link

An internal link that displays in red points to a page that does not exist by that name. Some red links come about due to errors (misspelling, or failure to check the exact name of the target article); these should be fixed by correcting the spelling, using a piped link or, if appropriate, creating a redirect. However many red links are perfectly legitimate, serving to point to an article which may exist in the future, and indeed encouraging editors to create such an article.

Legitimate red links should not be resolved by simply removing the bracket. If a red link is within the context of the article, and it is a topic with the potential to eventually be a neutral, verifiable and encyclopedic article, then the link should be kept. Such links do not have an expiration date, beyond which they must be "fixed". Red links should be removed only if they point to articles that are unlikely ever to be created, such as the names of book chapters, or if they would have little significance in the context of the present article even if they were created.

Note that red is only the default color for these links; logged-in users can change their preferences to select another color.

To make a link more useful to readers when no article currently exists, it may be useful to create a redirect to a relevant existing article or section, or to create a stub for the new article (check similar articles for conventions on naming and categorization).

Checking links as they are created

One of the commonest errors in linking occurs when editors do not check to see whether a link they have created goes to the intended location. This is especially true when a mistake is not obvious to the reader or to other editors. The text of links needs to be exact, and many Wikipedia destinations have a number of similar titles. To avoid such problems, which can be irritating for readers, the following procedure is recommended, especially for editors who are new to creating links.

1. Carefully key in the link.
2. Click on "Show preview".
3. In the display-mode, click on the links to check they go where you intend; if they do not, fix them. If a destination page does not appear to exist, do a quick search to determine whether the article has a differently worded title or the subject is treated in a section of another article. Adjust the link accordingly, or leave it as a red link.
4. Return to the "Show preview" page using your browser's return button.
5. Click on "Save page".

By following naming conventions, an internal link will be much more likely to lead to an existing article. When there is not yet an article about the subject, a good link will make the creation of a correctly named article much easier for subsequent writers.

Link maintenance

Linking and continual change are both central features of Wikipedia; however, continual change makes linking vulnerable to acquired technical faults and the provision of different information from that which was originally intended. This is true of both "outgoing" links (from an article) and "incoming" links (to an article).

• Outgoing links: These should be checked from time to time for unintended changes that are undesirable; if the opportunity arises to improve their formatting, appropriateness and focus, this should be done.
• Incoming links: Creating an article will turn blue any existing red links to its title (redlinks are usually created in the hope that an article will eventually be written). Therefore, when creating an article, it is wise to check "What links here" to identify such redlinks, if any, and that they are appropriate.

External links

Main page: Wikipedia:External links

Wikipedia is not a link collection and an article comprising only links is contrary to the "what Wikipedia is not" policy.

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://www.example.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://www.example.org www.example.org] produces www.example.org.

Link titles

Main page: Wikipedia:Embedded citations

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:

[2]

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 headings, two equal signs should be used to mark up the external links heading (see Headings elsewhere in the article).

If there is a dispute on the position of an embedded link, consider organizing alphabetically.

See Wikipedia:Citing sources#Embedded links for how to format these, and Wikipedia:Verifiability, which is policy.

Non-English-language sites

Webpages in English are highly preferred. Linking to non-English pages may still be useful for readers in the following 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 interpret them)
• when the webpage contains key or authoritative information found on no English-language site and is used as a citation (or when translations on English-language sites are not authoritative).

In such cases, indicate what language the site is in. For example:

• El País, a Spanish-language newspaper from Madrid

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>}}. For example, {{Languageicon|es}} displays as: Template:Languageicon. Alternatively, type {{xx icon}}, where xx is the language code. For example, {{pl icon}} gives: Template:Pl icon. See Category:Language icon templates for a list of these templates and the list of ISO 639 codes.

File type and size

If the link is not to an HTML file, identify the file type. Useful templates are available: {{PDFlink}}, {{DOClink}}, {{RTFlink}}. If a browser plugin is required to view the file, mention that as well.

If the link is to a large file (in the case of HTML, including the images), a note about that is useful too. Someone with a slow connection may decide not to use it.

Interwiki linking

Main pages: Wikipedia:Interlanguage links and Wikipedia:Interwikimedia links

Links to articles in other Wikimedia Foundation projects such as Wiktionary and Wikiquote can be done with special link templates such as Template:Wikiquote. These will display as a blue box with a logo. Similar templates exist for some free content resources that are not run by the Wikimedia Foundation. These boxes are formatted in light green to distinguish them from Wikipedia's official sister projects. A list of such templates can be found at Wikipedia:List of templates linking to other free content projects.

See also

• Help:Contents/Links
• Wikipedia:External links
• Wikipedia:Interlanguage links
• Wikipedia:Interwikimedia links
• Wikipedia:Red link
• Wikipedia:Walled garden
• Wikipedia:Dead-end pages, pages without internal links
• Wikipedia:Orphaned articles, pages without incoming links
• Wikipedia:Wikiproject Orphanage
• Wikipedia:WikiProject Integration
• Template:Deadend
• Template:Wikify
• Wikipedia is not an indiscriminate collection of information
• Wikipedia:Allwiki, the idea that every single word should be a link (historical)