CMS became a buzz word in the web development industry because of its benefits.
The definition of a CMS is an application (more likely web-based), that provides capabilities for multiple users with different permission levels to manage (all or a section of) content, data or information of a website project, or internet/intranet application.
Managing content refers to creating, editing, archiving, publishing, collaborating on, reporting, distributing website content, data and information.
An example of a CMS application is a Web Application that provides the following administration, control panel or website management functionalities:
Content Management Systems are used by multiple agencies and companies for various reasons, most commonly for websites and blogs. In fact, this very site was built on WordPress. One of the many different systems that there are available.