Capabilities

A WCMS is a software system used to manage and control a large, dynamic collection of Web material (HTML documents and their associated images). A CMS facilitates document control, auditing, editing, and timeline management. A WCMS provides the following key features:

Automated templates
Create standard output templates (usually HTML and XML) that can be automatically applied to new and existing content, allowing the appearance of all of that content to be changed from one central place.
Easily editable content
Once content is separated from the visual presentation of a site, it usually becomes much easier and quicker to edit and manipulate. Most WCMS software includes WYSIWYG editing tools allowing non-technical individuals to create and edit content.
Scalable feature sets
Most WCMS software includes plug-ins or modules that can be easily installed to extend an existing site's functionality.
Web standards upgrades
Active WCMS software usually receives regular updates that include new feature sets and keep the system up to current web standards.
Workflow management
Workflow is the process of creating cycles of sequential and parallel tasks that must be accomplished in the CMS. For example, a content creator can submit a story, but it is not published until the copy editor cleans it up and the editor-in-chief approves it.
Document management
CMS software may provide a means of managing the life cycle of a document from initial creation time, through revisions, publication, archive, and document destruction.
Content virtualization
CMS software may provide a means of allowing each user to work within a virtual copy of the entire Web site, document set, and/or code base. This enables changes to multiple interdependent resources to be viewed and/or executed in-context prior to submission
http://en.wikipedia.org/wiki/Web_content_management_system