You may be looking for one of the following pages:

• $wgLanguageCode - The parameter to set MediaWiki's interface language
• $wgDefaultUserOptions - Configuration setting that can be used for the default user language.
• {{#language }} –  Magic word to display a localized language name from its short code
• Manual:Language - Information about the concepts of interface and site/page content languages
• Unrecognised languages
• Category:Internationalization extensions - Several extensions to add some multilingual features to MediaWiki
• Project:Language policy - The MediaWiki.org policy about languages
• Wikimedia Language engineering - The Internationalization and Localization team
• Programming languages