Joomla! is a popular open source CMS. Joomla! is known for its robustness and flexibility, enabling its uses to go beyond that of common content management and publishing.
At its core, the Joomla! framework possesses an MVC architecture which allows it to be built as a three-tiered system comprised of Framework, Application, and Extension layers. This structure allows Joomla! to be fully modular in creating components, modules, plugins, and UI themes.
As mentioned, the flexibility of Joomla! enables it to be used to build a variety of web sites: blogs, magazines, and news-type publications; Web portals; forums and social networks; retail and auctions.