Whether you need to set up a blog, a portal for some specific usage, or any other website, which content management system is right for you? is a question you are going to ask yourself early on. The most well-known and widely used open source content management system (CMS) platforms are: Joomla, Wordpress, and Drupal. They are all based on PHP and MySQL and offer a wide range of options to users and developers alike.
To help you choose between these three excellent open source CMS platforms, I've written a comparison based on this criteria: installation complexity, available plugin/themes, ease of use, and more.