What is a CMS?
A content management system (CMS) allows publishing, editing, and modifying content as well as site maintenance from a central page. It provides a collection of procedures used to manage work flow in a collaborative environment. These procedures can be manual or computer-based. — Wikipedia (2012-03-15)
In my career as a programmer, I have come across more than a few CMS packages built with php. I have chosen three to feature my abilities with. These are Drupal, Joomla, and Wordpress.