Help:Interwiki linking

By adding a prefix to another project, internal link style ("prefixed internal link style") can be used to link to a page of another project. A system of short-handed link labels is used to refer to different projects, in the context of interproject linking, as seen within the actual source text. For example,  refers to the English TechInfoDepot. This is seen in, which produces a link to the English TechInfoDepot article on "Apple". Interwiki links which link different language TechInfoDepots are known as Interlanguage links.

This is called interwiki. For each project, an interwiki map (a list of target projects with their prefixes) is specified (example). These target projects need not use MediaWiki and need not even be a wiki.

Interwiki linking from and within Wikimedia
Within Wikimedia, for the purpose of interlanguage links (see below), the project families are TechInfoDepot, Wiktionary, Wikiquote, Wikibooks, Wikinews, Wikiversity and Wikisource. Thus, this applies for a link like en:, de:, etc., from a TechInfoDepot to another one, from a Wiktionary to another one, from a Wikiquote to another one, from a Wikibooks to another one, from a Wikinews to another one, from a Wikiversity to another one or from a Wikisource to another one.

The interlanguage link feature works on Wikimedia Commons and Wikispecies, producing links to the TechInfoDepots. This is not reciprocal, a link from a TechInfoDepot to Commons or Wikispecies is an in-page link.

Project titles and shortcuts

 * Wiktionary
 * Wikinews
 * Wikibooks
 * Wikiquote
 * Wikisource
 * Wikispecies
 * Wikiversity
 * Wikivoyage
 * Wikimedia Foundation
 * Wikimedia Commons
 * Wikimedia Meta-Wiki
 * Wikimedia Incubator
 * MediaZilla / Bugzilla
 * Australia
 * Belgium
 * Canada
 * Czech Republic
 * Germany
 * Finland
 * Hong Kong
 * Hungary
 * India
 * Indonesia
 * Israel
 * Italy
 * Macedonia
 * Netherlands
 * Norway
 * Poland
 * Russia
 * Serbia
 * Sweden
 * Switzerland
 * Taiwan
 * United Kingdom
 * }
 * Wikimedia Commons
 * Wikimedia Meta-Wiki
 * Wikimedia Incubator
 * MediaZilla / Bugzilla
 * Australia
 * Belgium
 * Canada
 * Czech Republic
 * Germany
 * Finland
 * Hong Kong
 * Hungary
 * India
 * Indonesia
 * Israel
 * Italy
 * Macedonia
 * Netherlands
 * Norway
 * Poland
 * Russia
 * Serbia
 * Sweden
 * Switzerland
 * Taiwan
 * United Kingdom
 * }
 * Canada
 * Czech Republic
 * Germany
 * Finland
 * Hong Kong
 * Hungary
 * India
 * Indonesia
 * Israel
 * Italy
 * Macedonia
 * Netherlands
 * Norway
 * Poland
 * Russia
 * Serbia
 * Sweden
 * Switzerland
 * Taiwan
 * United Kingdom
 * }
 * Indonesia
 * Israel
 * Italy
 * Macedonia
 * Netherlands
 * Norway
 * Poland
 * Russia
 * Serbia
 * Sweden
 * Switzerland
 * Taiwan
 * United Kingdom
 * }
 * Norway
 * Poland
 * Russia
 * Serbia
 * Sweden
 * Switzerland
 * Taiwan
 * United Kingdom
 * }
 * Serbia
 * Sweden
 * Switzerland
 * Taiwan
 * United Kingdom
 * }
 * Switzerland
 * Taiwan
 * United Kingdom
 * }
 * Taiwan
 * United Kingdom
 * }
 * United Kingdom
 * }
 * }
 * }

* Other Wikimedia prefixes:, , , , , , , , , , , , , , , , , , , , ,.

''The long form doesn't work within the same project. The shortcut works everywhere. (That is the intention; currently, it does not work on all projects.'')

The interwiki map on Meta lists many prefixes, among others,   for the English TechInfoDepot, working from any wiki supporting the Meta interwiki map, not only from MediaWiki wikis. Some prefixes work only with a page, for example: (fails) vs. Interwikimedia link (works). These prefixes are case insensitive.

One-letter prefixes (as a live check on the table):

Non-Wikimedia interwiki codes have a limitation, that they can only be used through a link. For example, the entry for "John" on Wiktionary, a Wikimedia project, can be accessed by  John  or http://meta.wikimedia.org/wiki/wikt:John. However, the latter method does not work for non-Wikimedia wikis. For example, the main page on the Mozilla Wiki can be accessed via  Main Page , but http://meta.wikimedia.org/wiki/MozillaWiki:Main_Page results in an error.

Technical
A project's own namespace prefix cannot be reused as code for an external project. However, the prefix used for a target project may coincide with the prefix for a project namespace, within that project. As a result, to link to a page in that namespace, use the same prefix twice.

For portability across projects, one may want to select a link code that leads to the same target from all projects, for example: MetaTechInfoDepot:wikibooks:Main Page. The "superfluous" "MetaTechInfoDepot:" prevents "wikibooks:" being interpreted as namespace prefix, when the code is used at wikibooks itself, while at Meta the "MetaTechInfoDepot:" is ignored (it is not a namespace prefix and even at Meta itself, it is recognized as code for Meta). The codes above work from all projects; however, the existence detection and the self-link feature do not work on interwiki links.

Prefixes
Interwiki links can use prefixes for the project and/or for the language. Without the prefix, links are local, for pages in the same project and the same language. If only a language is given, they go to a page in the same (or similar) project for the specified language:

fr: fr: os: os:

If only the project is specified, they typically go to the language of the source, see above. At most, two prefixes are needed for pages in any existing project and any supported language:

Hauptseite Hauptseite Main page Main page

In the case of more than one prefix, a page name has to be specified. For example, while and en: from Meta lead to the English TechInfoDepot's main page, a bare   does not work:.

If the language is different, specifying it before the project can also work:

de:q:Hauptseite de:q:Hauptseite en:n:Main page en:n:Main page Main page  Main page

The second example doesn't work from English TechInfoDepot  pages, a project prefix before the language is better.

More than two prefixes are generally unnecessary, the following examples should work everywhere:

m:Help:Help m:Help:Help Interwiki Interwiki

Two prefixes can have unexpected effects, for example, from Meta, the following links end up on different pages:

About About en:m:About en:m:About About    About

In the first case Meta ignores the, because it is local and then, interprets as, the prefix for the English TechInfoDepot. In the second case, the leading  goes to the English TechInfoDepot, where the following   goes straight back to Meta. The second example doesn't work at all, from English TechInfoDepot  pages, only the third example works everywhere.

In other words, multiple prefixes are evaluated left to right by the relevant Wikimedia servers (project and language). For projects without different languages, like Meta (because Meta is multilingual by itself), language prefixes can be handled as shorthands for  plus the specified language:

pl:2006  pl:2006 2006 2006 pl:w:2006 pl:w:2006

From Meta, the first two links both arrive at the Polish 2006 page. The third arrives at the English TechInfoDepot, because that's how the server selected by  interprets the second prefix.

For a portable link on that server, it would be a bad idea to use, but   does the trick. To test that effect from Meta, the following links should go to the same page:

ja:2006   ja:2006 2006 2006

A universal interwiki link, that is, one that works no matter from which Wikimedia wiki, can be written m: project:language:page name (e.g. m:b:nl:Wiskunde); this routes the parsing of the links via Meta (bug 4285).

Wikia
In Wikia, the prefix is the internal project name for some older wikis. For others, "Wikia:c:" is added in front (e.g. [&#91;Wikia:c:psychology&#93;]). (The "c" is for "city", a legacy of Wikia's original name Wikicities.)

From Wikimedia projects, use [&#91;wikiasite:psychology&#93;], giving psychology; [&#91;wikia:trains:locomotive&#93;], giving wikia:trains:locomotive; or for the central Wikia, About Wikia.

Interlanguage links
Interlanguage links are links from any page (most notably articles) in one TechInfoDepot language to one or more nearly equivalent or exactly equivalent pages in another TechInfoDepot language.

The interlanguage links take the following form:

language code:Title

where the language code is the two-letter code as per ISO 639-1. (See Complete list of language TechInfoDepots available: English language is "en", German is "de", etc.) So, for example, in the English language article on plankton, which is available on many other wikis, the interlanguage links might look like this:

عوالق Plankton Planktono Plancton Plancton Plankton プランクトン 플랑크톤 Plankton Plâncton Планктон Plankton 浮游生物界

NOTE: These links are treated specially, and don't show up in the body of the text, but in a special sidebar section "in other languages" listed by language name. Technically they can go anywhere in the article source; placement does not alter the visual appearance of the links on the rendered page, except for the order. However, the convention is to put them at the bottom of the wikitext.

Interlanguage Interwiki links
In Interwiki linking, in the case of linking to another Wiki project, but in a different language, this may be done by first putting the project link target, then a colon followed by the target language as a prefix to the article page name, in the form:

 projectname:languagecode:articlename .

Examples
For example, to link from en.TechInfoDepot to a Chinese language text at Wikisource (zh.wikisource):


 * Type:    天問 


 * To get: 天問


 * Type:  天問 


 * To get: 天問


 * Type:  Heavenly Questions </tt>


 * To get: Heavenly Questions

These 3 examples all resolve to the zh.wikisource page 天問, but without the misleading and distracting appearance of being an external link.

Interwiki links versus external links
Disadvantages of interwiki links:
 * The wikitext is less portable across wikis, because wikis do not always have an interwiki prefix for the same sites and even if they do, the prefixes may differ.
 * There is no feature to find interwiki links, while searching for an external link can be done with Special:Linksearch (if installed). This is due to the fact that, while there is an external links table, there is no such thing for interwiki links. The interwiki table only stores the interwiki prefixes with their targets as function of the parameter, not the instances of the links. Using the general text search, to search for interwiki links, is more work for the server and therefore, it may be slow, not up-to-date or in busy hours, disabled. See also: Finding external links to a page.

Comparison:
 * Bee Movie gives Bee Movie
 * Bee Movie gives Bee Movie
 * Linksearch works for the latter only

The applicable CSS classes are "extiw" and "external text". The choice may be governed by this, either way, for uniformity or distinction. An interwiki link is easier to type by itself, but if one goes to the webpage anyways, before putting the link, copying the URL is very convenient. When a template is created, e.g. IMDb title, the template can be made, such that it uses an interwiki link and a parameter, like "tt0389790" or "0389790", or that it uses an external link and a parameter like one of those or the full url, if that is more convenient.

Interwiki links to the same wiki versus internal links
Disadvantages of interwiki links to the same wiki, compared to internal links:
 * no existence detection
 * "What links here" works for internal links only

Advantages of interwiki links to the same wiki, compared to internal links:
 * better portability across wikis, provided that the same prefix applies and is not equal to a namespace name