MediaWiki is the software behind Wikipedia and many other wikis, including the File Formats Wiki (this wiki). It is a free, open-source program, which works in a number of operating systems. It is implemented in PHP, and uses a database for back-end storage (it will work with several database systems including MySQL and SQLite). Articles edited in MediaWiki use its own form of wiki markup, using double square brackets for wiki links and single square brackets for web links, as well as a number of other formatting and structural markup elements (including some very complex things such as tables and templates). Newer versions have a rich-text editor to allow easier editing without the editors needing to know all the arcane details of the markup, though its deployment in popular wikis remains controversial since old-timer editors (especially those of a programming background) often prefer to edit the markup by hand.
Many extensions exist for MediaWiki to add additional features to it.
A lot of the configuration of an installation of MediaWiki is in the file