CMS is a software that is capable of supportive creation of documents and any other such content. Its main use till date has been to write user manuals, help documents and content for Web Pages. It is used to basically manage the content of the website i.e. 'web content'. All sorts of business documents can also be prepared using the CMS. It's use is not restricted to the operational manuals, technical manuals etc.
It once originated as a tool for website publishing and its management system. With times changing, it is now referred to a range of techniques and different technologies like groupware, wiki systems and portals.