A CMS is a tool that enables a variety of (centralised) technical and (de-centralised) non technical staff to create, edit, manage and finally publish (in a number of formats) a variety of content (such as text, graphics, video, documents etc), whilst being constrained by a centralised set of rules, process and workflows that ensure coherent, validated electronic content. 

A content management system (CMS) is computer software used to create, edit, manage, and publish content in a consistently-organized fashion. [1] CMSs are frequently used for storing, controlling, versioning, and publishing industry-specific documentation such as news articles, operators' manuals, technical manuals, sales guides, and marketing brochures. The content managed may include computer files, image media, audio files, electronic documents, and Web content.

A CMS may support the following features:

• Adding/editing/removing pages or web content without technical knowledge;
• identification of all users and their content management roles;
• the ability to assign roles and responsibilities to different content categories or types;
• definition of workflow tasks for collaborative creation, often coupled with event messaging so that content managers are alerted to changes in content (For example, a content creator submits a story, which is published only after the copy editor revises it and the editor-in-chief approves it.);
• the ability to track and manage multiple versions of a single instance of content;
• the ability to publish the content to a repository to support access to the content (Increasingly, the repository is an inherent part of the system, and incorporates enterprise search and retrieval.);
• separation of content's semantic layer from its layout (For example, the CMS may automatically set the color, fonts, or emphasis of text.).