Joomla is an open-source Content Management System that has been designed with more experienced developers in mind. It is not quite as comprehensive and advanced as Drupal, but requires more development knowledge than WordPress.
The installation process is relatively straight forward, taking less than 10 minutes to download and install on a server. On first use the Joomla back-end can be quite cumbersome to navigate, so takes a bit of getting used to.
Joomla is widely acknowledged as the second most used content management system in the world, second only to WordPress.
Are there many extensions available?
Although not anywhere near as many as WordPress, the Joomla content management system has a generous amount of extensions available. In total there are over 7,800 free and commercial extensions to choose from. The extensions available on the Joomla website range from Access & security, to Admin and Ecommerce.
What technology is Joomla based on?
Joomla is based on PHP and MySQL, the same technologies that WordPress and Drupal are based on.