A Joomla component is the application that generates the main content of a page, exactly one component runs per page. Most Joomla features, such as articles, contacts, users and menus, are components, making them the core building blocks of the CMS. Components follow the MVC pattern and are split into a front-end (site) and back-end (administrator) part. They are identified by the com_ prefix, for example com_content, and are selected through the URL's option parameter. Understanding how one component works helps you customise, extend and troubleshoot almost any Joomla extension.
