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