PostNuke is an advanced content management system (CMS) written in PHP and released as open source under the GPL. It runs on any operating system and web server with PHP and MySQL support and provides extensive tools and features that enable quick and easy dynamic website development. PostNuke's core system can be easily customized and extended through the use of modules, and the entire site interface can be designed and managed using a theme templating system such as the built-in Xanthia module or AutoTheme add-on module. PostNuke is XHTML compliant, provides support for multiple languages, and is known for its superior focus on security. If you're seeking a mainstream CMS with a solid feature set, an extensive third-party developer base, and an active community of thousands of friendly users, PostNuke is for you. It should be noted that PostNuke aims to provide small core functionality, which is then extended by third party additions. As such, PostNuke is much more flexible than at first appears when downloading the initial distribution