MediaWiki - powers Wikipedia

MediaWiki is powers Wikipedia.org. MediaWiki is designed to be run on a large server farm for a website that gets millions of hits per day. MediaWiki is an extremely powerful, scalable software and a feature-rich wiki implementation. Pages use MediaWiki's wikitext format, so that users without knowledge of XHTML or CSS can edit them easily.

When a user submits an edit to a page, MediaWiki writes it to the database, but without deleting the previous versions of the page, thus allowing easy reverts in case of vandalism or spamming. MediaWiki can manage image and multimedia files, too, which are stored in the filesystem. For large wikis with lots of users, MediaWiki supports caching and can be easily coupled with Squid proxy server software.