Content management system (CMS) describes computer software system that allows people to more easily change and update content, especially on their websites. When the content and/or the number of contributors grows large, a CMS helps collect and create the content in ways that makes it easy to reuse. A CMS allows a team of contributors to work on the same pages without conflicting (check-in/check-out and workflow control). It can schedule pages to appear and disappear at designated times, and archive the old pages with versioning and revision control. Reuse of content means an item can be edited in one place and be published instantly in many places. But it also means that the different versions of the content can be formatted properly for multiple delivery channels, including the web (HTML and PDF), print, wireless handheld devices, and cell phones.

News portal software (slash-alikes and the -nuke family) are a form of community CMS, as are weblog tools (usually for personal publishing) and Wikis (usually for teams of contributors).

Some CMSs edit whole web pages, others edit a content template for a page and individual content elements. Both kinds may have form-based text editing, source editing of the markup language, or WYSIWYG (what-you-see-is-what-you-get) visual editing. Smaller CMSs tend to be page-oriented and store HTML. Enterprise CMSs use content templates and usually store content elements as information chunks in XML. Some systems tag and store the information with RDF (Resource Description Framework) metadata for the Semantic Web.

Both open-source and proprietary solutions for content management systems are available.