TYPO3 is a free and open source web content management framework based on PHP. It is released under the GNU General Public License. It can run on several web servers, such as Apache or IIS, on top of many operating systems, among them Linux, Microsoft Windows, FreeBSD, Mac OS X and OS/2.
TYPO3 is, along with Drupal, Joomla! and Wordpress, among the most popular content management systems worldwide, however it is more widespread in Europe than in other regions. The biggest market share can be found in German-speaking countries.
TYPO3 is credited to be highly flexible - It can be extended by new functions without writing any program code. Also, the software is available in more than 50 languages and has a built-in localization system - therefore supports publishing content in multiple languages. Due to its features, scalability and maturity, TYPO3 is used by to build and manage websites of different types and size ranges, from small sites for individuals or nonprofit organizations to multilingual enterprise solutions for large corporations. According to the ability to support a corporate environment, it is classified as an enterprise level content management system.