Digital rights management (DRM) is a term referring to various access control technologies that are used to restrict the usage of proprietary software, hardware, or content. The term "DRM" encompasses technologies that control the use, modification, and distribution of copyrighted works, as well as systems within devices that enforce these policies. The term is also sometimes referred to as "copy protection", "technical protection measures", "copy prevention", or "copy control", although the correctness of doing so is disputed.