Joomla is a free and open-source content management framework (CMS) for publishing web content. It is built on a model–view–controller web application framework that can be used independently of the CMS.
Joomla is written in PHP, uses object-oriented programming (OOP) techniques (since version 1.5) and software design patterns, stores data in a MySQL, MS SQL (since version 2.5), or PostgreSQL (since version 3.0) database, and includes features such as page caching, RSS feeds, printable versions of pages, news flashes, blogs, polls, search, and support for language internationalization.
A Joomla template is a multifaceted Joomla extension which is responsible for the layout, design and structure of a Joomla powered website. While the CMS itself manages the content, a template manages the look and feel of the content elements and the overall design of a Joomla driven website. The content and design of a Joomla template is separate and can be edited, changed and deleted separately.
The template is where the design of the main layout for a Joomla site is set. This includes where users place different elements (components, modules, and plug-ins), which are responsible for the different types of content. If the template is designed to allow user customization, the user can change the content placement on the site, e. g., putting the main menu on the right or left side of the screen.