Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. MediaWiki is a free web-based wiki software application used by all projects of the Wikimedia Foundation, and many other wikis. It is written in the PHP programming language and uses a database. The first version of the software was deployed to serve the needs of the free content Wikipedia encyclopedia in 2002. Today, it has also been deployed by many companies as a content management system for internal knowledge management. Notably, Novell uses it to operate several of its high-traffic websites. As of 2009, more than 2,000 wiki sites used MediaWiki. Some educators have also assigned students to use MediaWiki for collaborative group projects.