Digital rights management (DRM), also known unofficially as digital restrictions management,1 is a type of anti-feature that is designed to restrict what you can do with a piece of software or media. DRM usually comes in the form of non-free software, since it relies on the obfuscation of its own inner workings to be effective.
DRM is usually employed to enforce the commercial preferences of copyright holders,2 with the result that it prevents certain fair use of copyrighted material, thwarts assistive technologies from making media more accessible, enables surveillance, and can even entirely prevent you from reading, watching, or listening to copies of media you have purchased.3