This document provides an overview of Joomla, an open source content management system (CMS). It defines what a CMS is and explains that Joomla allows users to create, edit, and publish various types of content. Key features of Joomla include user management, search, language support, content organization, media management, polls, links, banners, syndication, an help system, and extensibility through third-party extensions. Joomla also has a flexible template system and is used by many websites, including joomla.org, linux.com, and Harvard University sites.