From Wiki

MediaWiki is free server-based software, that is licensed under the GNU General Public License (GPL). It's designed to be run on a large server farm for a website that gets millions of hits per day. MediaWiki is an extremely powerful, scaleable software and a feature-rich wiki implementation, that uses PHP to process and display data stored in its MySQL database.

Some of these article refer to vBulletin, and integration between MediaWiki and vBulletin using vbWiki (Standard or Pro).

For information about vBulletin to the vBulletin Portal.

For information about vbWiki and vbWiki Pro go to vbWiki Pro Portal.

[edit] Links to existing MediaWiki resources on the web

• Official MediaWiki website
• MediaWiki Downloads