A great feature of Joomla is the Module Manager, which allows you to insert various functions into your website. Perhaps you want to include a search bar, or a latest news updates box, or a menu contained within your websites side bar. The module manager is where all this action begins.
Joomla already has a whole lot of great default modules you can begin using straight away, and there are also literally thousands of other modules and plugins you can download from the Joomla Extensions Directory that have been submitted by many Joomla users around the world.
When you install and start using Joomla there are many features built into it that make your site useful from, content editing and management to user controls and now access control levels in Joomla 1.6.
To extend Joomla's core functionality, there are extensions available for web administrators to install and configure in their Joomla websites.
These extensions allow for an also unlimited number of new functions that can be added onto Joomla's core list of functions.