According to wikipedia “A content management system (CMS) is a computer software system for organizing and facilitating collaborative creation of documents and other content. A content management system is frequently a web application used for managing websites and web content, though in many cases, content management systems require special client software for editing and constructing articles. The market for content management systems remains fragmented, with many open-source and proprietary solutions available.”

Most CMS systems are written in PHP/Perl and MySQL database software. According to us following are the best open source content management system:

• Drupal
• Xoops
• Mambo
• PostNuke

For more information and in depth comparisons of CMS see:

• http://www.opensourcecms.com/ – You can try various open source CMS software before install. Includes both admin and user page access.
• http://www.cmsmatrix.org/ – You can discuss, rate, and compare the various CMS software systems available on the market today including open source CMS systems.