Help:Version
Version is a special page that displays the version of MediaWiki and its dependencies and lists the installed skins, extensions and libraries, as well as the parser extension tags and parser function hooks provided by the installed extensions.
The information displayed about extensions is retrieved from their extension.json file and the extensions are grouped by the type defined in extension.json.
The data displayed by the Version special page is also available programmatically via API:Siteinfo.