Joomla! is a free and open source content management system for publishing content on the World Wide Web and intranets as well as a model–view–controller (MVC) Web application framework. It is written in PHP, stores data in MySQL and includes features such as page caching, RSS feeds, printable versions of pages, news flashes, blogs, polls, search, and support for language internationalization.

Within its first year of release, Joomla was downloaded 2.5 million times. Over 5,000 free and commercial plug-ins are available for Joomla.

Joomla can be installed manually from source code on a system running a web server which supports PHP applications. Manual installation usually requires more time and experience than other alternatives such as installing Joomla from a package management system or using a TurnKey Joomla appliance which pre-integrates Joomla and its dependencies as a ready-to-use system.

There are numerous web hosting companies who provide a control panel which automates the deployment of a basic Joomla web site.

Joomla can also be installed via the Microsoft Web Platform Installer which installs Joomla on Windows and IIS. The Web PI will automatically detect any missing dependencies such as PHP or MySQL then install and configure them before installing Joomla.