A Joomla template is like any other template in other words at it's simplest its just an HTML page with CSS that you add special PHP tags to. Joomla templates are made up of many parts that come together and render into one. This is true for both Front End templates and Back End templates.

Out of the box, Joomla does a great job of managing the content needed to make your website sing. But for many people, the true power of Joomla! lies in the application framework that makes it possible for thousands of developers around the world to create powerful add-ons that are called extensions. An extension is used to add capabilities to Joomla! that do not exist in the base core code.