A web content management system (WCMS) is a software system that provides website authoring, collaboration, and administration tools designed to allow users with little knowledge of web programming languages or markup languages to create and manage website content with relative ease. A robust WCMS provides the foundation for collaboration, offering users the ability to manage documents and output for multiple author editing and participation.
Most systems use a content repository or a database to store page content, metadata, and other information assets that might be needed by the system.
A presentation layer (template engine) displays the content to website visitors based on a set of templates, which are sometimes XSLT files.
Most systems use server side caching to improve performance. This works best when the WCMS is not changed often but visits happen regularly.
Administration is also typically done through browser-based interfaces, but some systems require the use of a fat client.
A WCMS allows non-technical users to make changes to a website with little training. A WCMS typically requires a systems administrator and/or a web developer to set up and add features, but it is primarily a website maintenance tool for non-technical staff.
Courtesy : to wikipedia