A wide-ranging term that generally refers to the practice of defining, creating, organizing, securing, reviewing, approving, publishing, and delivering content.
Content management is not specific to digital technology – librarianship, for instance, is a form of content management–but is most often used in a digital context. Content management specifically around web content is sometimes abbreviated WCM.
A content management system is software that attempts to automate many of the tasks around this discipline. A content manager is a person tasked with performing this discipline.