MediaWiki

MediaWiki is a free and open source wiki software maintained by the Wikimedia Foundation and used for Wikipedia and other Wikimedia projects, as well as a variety of other wikis (including Knowino).

Notable MediaWiki-based sites

 * Citizendium
 * Conservapedia
 * Knowino
 * Meta-Wiki
 * RationalWiki
 * Wikimedia Commons
 * Wikinews
 * Wikipedia
 * Wikiquote
 * Wikisource
 * Wiktionary