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,
en: refers to the English Wikipedia. This is seen in
[[en:Apple]], which produces a link to the English Wikipedia article "Apple". Interwiki links which link different language Wikipedias 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.
Within Wikimedia, for the purpose of interlanguage links (see below), the project families are Wikipedia, Wiktionary, Wikiquote, Wikibooks, Wikinews, Wikiversity and Wikisource. Thus, this applies for a link like en:, de:, etc., from a Wikipedia 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 Wikipedias. This is not reciprocal, a link from a Wikipedia to Commons or Wikispecies is an in-page link.
* Other Wikimedia prefixes: betawikiversity:, download:, dbdump:, gerrit:, mail:, mailarchive:, outreach:, otrs:, OTRSwiki:, quality:, spcom:, ticket:, tools:, tswiki:, svn:, sulutil: rev:, wmania:, wm2005:, wm2006:, wm2007:, wm2008:, wm2009:.
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,
[[wikipedia:]] ([[wikipedia:]]) for the English Wikipedia, working from any wiki supporting the Meta interwiki map, not only from MediaWiki wikis. Some prefixes work only with a page, for example: wikipediawikipedia: (fails) vs. wikipediawikipedia:Interwikimedia link (works). These prefixes are case insensitive.
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 [[wikt: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 [[MozillaWiki:Main Page]], but http://meta.wikimedia.org/wiki/MozillaWiki:Main_Page results in an error. In these cases, Special:Search can be used (http://meta.wikimedia.org/wiki/Special:Search/MozillaWiki:Main_Page). You can see the Interwiki special page for a list of "forward" and "non-forward" prefixes.
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: MetaWikipedia:wikibooks:Main Page. The "superfluous" "MetaWikipedia:" prevents "wikibooks:" being interpreted as namespace prefix, when the code is used at wikibooks itself, while at Meta the "MetaWikipedia:" 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.
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:
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:
[[s:de:Hauptseite]] s:de:Hauptseite [[b:en:Main page]] b:en:Main page
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]] [[n:en:Main page]] n:en:Main page
The second example doesn't work from English Wikipedia
w:en: 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 [[w:Interwiki]] w:Interwiki
Two prefixes can have unexpected effects, for example, from Meta, the following links end up on different pages:
[[m:en:About]] m:en:About [[:en:m:About]] [[:en:m:About]] [[m:About]] m:About
In the first case Meta ignores the
m:, because it is local and then, interprets
w:en:, the prefix for the English Wikipedia. In the second case, the leading
en: goes to the English Wikipedia, where the following
m: goes straight back to Meta. The second example doesn't work at all, from English Wikipedia
w:en: 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
w: plus the specified language:
For a portable link on that server, it would be a bad idea to use
:pl: does the trick. To test that effect from Meta, the following links should go to the same page:
[[:ja:2006]] ja:2006 [[:ja:ja:2006]] ja:ja: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).
In Wikia, the prefix is the internal project name for some older wikis. For others, "Wikia" is added in front (e.g. [[Wikia:psychology]]).
Interlanguage links are links from any page (most notably articles) in one Wikipedia language to one or more nearly equivalent or exactly equivalent pages in another Wikipedia language. Prior to February 2013, they were generated using special link markup within articles, taking the form
[[language code:Title]], where the language code is the two-letter code as per ISO 639-1. (See Complete list of language Wikipedias 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:
[[ar:عوالق]] [[de:Plankton]] [[eo:Planktono]] [[es:Plancton]] [[fr:Plancton]] [[nl:Plankton]] [[ja:プランクトン]] [[ko:플랑크톤]] [[pl:Plankton]] [[pt:Plâncton]] [[ru:Планктон]] [[simple:Plankton]] [[zh:浮游生物界]]
These links do not show up in the article, but instead populate the "Languages" list on the sidebar. While they can be theoretically located anywhere in the article, they were typically placed near the bottom.
As of February 2013, the use of "local" links for interlanguage linking has been deprecated, with interlanguage link data being centralized on Wikidata, a structured knowledge base project. Pages with their interlanguage links on Wikidata display an "Edit links" button under the language list.
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:
For example, to link from en.Wikipedia to a Chinese language text at Wikisource (zh.wikisource):
- Type: [[wikisource:zh:天問]]
- To get: wikisource:zh:天問
- Type: [[wikisource:zh:天問|天問]]
- To get: 天問
- Type: [[wikisource:zh:天問|Heavenly Questions]]
- 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.
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.
- [[imdbtitle:0389790|Bee Movie]] gives Bee Movie
- [http://www.imdb.com/title/tt0389790 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. Template:IMDb title (backlinks, ), 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.
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
|This page is referenced from the Wikipedia:Glossary.|
- mw:Help:Interwiki linking and meta:Help:Interwiki linking
- Wikimedia sister projects
- m:Templates for linking to sister projects
- InterWikimedia links
- Wikipedia:Help desk — to ask questions about using interwiki links in articles if you weren't able to find the information you need on this help page.