Help:Interwiki linking
Basics
An interwiki link (or for short, iwiki or iw) is a special link from a content page (not a talk page) on the English Wiktionary to a similar page on another Wikimedia project. These links do not show up in the page itself, but are displayed in a toolbar to the left. Interwiki links are placed right at the end of the page's wikitext, one on each line.
Interlanguage links consist of the language prefix and then the name of the page (i. e. [[de:word]]. If you want to link to a different Wiktionary inline in the form of a blue link instead of an interwiki, for example on discussion pages, add a colon (:) directly after the two left square brackets ([[), i. e. [[:de:word]] (which becomes de:word).
You can also link to other projects of the Wikimedia Foundation using their respective prefixes. For example [[q:de:Hauptseite]] links to the German Wikiquote (please note the project prefix should come first).
See the meta-wiki page for available project prefixes and details if interwiki linking. For a complete list of current languages and language codes, see the Wikipedia List of Wikipedias.
Entries
In the main namespace, interwikis always link to pages entries exactly the same title, even if that page is redirect page. This is different from Wikipedia's translation-based method. It is not necessary to add such links to the English Wiktionary by hand as this is done by the internal system. In the Category, Wiktionary, Help, and other namespaces, it is dealt with on Wikidata.
Other namespace pages
Interwiki links in other namespaces, such as for templates, link pages with similar functionality (not necessarily identical titles). For details about place interwiki links on templates, see Help:Documenting templates.
es:Ayuda:Enlaces interwiki he:עזרה:בינוויקי pt:Ajuda:Guia de edição/Interwikis