This stands for Content Management System. Some of the top CMSs are: Drupal, WordPress, Adobe CQ5 WCM, SiteCore, SharePoint, Joomla, Expression Engine, Kentico, Interwoven and Vignette. Some are open source and free and some costs tens of thousands of dollars a year. A CMS is a database application that makes it easier to build and manage websites as well as create dynamic user experiences. For more info about CMSs and how they work.
Make sure the CMS you are using is right for your company or organization. Some of the variables include cost, functionality, extensibility, ability to customize and support.