A Content Management System (CMS) is a software tool used to create, manage, and modify digital content without specialized technical knowledge. Key functions of a CMS include content creation, content storage, workflow management, and publishing. It allows multiple users to collaborate on the contents, supports SEO optimization tools, and often features template management for consistent styling. Examples of popular CMS platforms are WordPress, Joomla, and Drupal, which empower businesses to maintain engaging websites efficiently.