Complex sentence: Joomla is a free and open source content management system (CMS) 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.
Split into simpler sentences: Joomla is a free and open-source content management system (CMS) for publishing web content. It is built on a model--view--controller web application framework that can also be used independently.