Joomla is a free and open source content management framework (CMF) for publishing content on the World Wide Web and intranets and a model–view–controller (MVC) Web application framework that can also be used independently.
A template controls the overall look and layout of a site. It provides the framework that brings together common elements, modules and components as well as providing the cascading style sheet for the site. Both the front-end and the back-end of the site have templates.
When Joomla! is first installed several templates are automatically included. You can find many more templates at other websites. Some are available without charge under various licenses, and some are for sale. In addition, there are many developers available who can make custom templates. You can also make your own template.
Templates are managed with the Template Manager, which is located on the Extensions menu in the back-end (administrator) area of your site.