A content management system (Web CMS) is a bundled or stand-alone application to create, deploy, manage and store content on Web pages. Web content includes text and embedded graphics, photos, video, audio, and code (e.g., for applications) that displays content or interacts with the user. A Web CMS may catalog and index content, select or assemble content at runtime, or deliver content to specific visitors in a requested way, such as other languages. Web CMSs usually allow client control over HTML-based content, files, documents, and Web hosting plans based on the system depth and the niche it serves.
So it's a way for you to update your site in seconds!