Digital rights management (DRM) is a set of access control technologies for restricting the use 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 use of digital rights management is not universally accepted. Proponents of DRM argue that it is necessary to prevent intellectual property from being copied freely, just as physical locks are needed to prevent personal property from being stolen, that it can help the copyright holder maintain artistic control, and that it can ensure continued revenue streams. Those opposed to DRM contend there is no evidence that DRM helps prevent copyright infringement, arguing instead that it serves only to inconvenience legitimate customers, and that DRM helps big business stifle innovation and competition. Furthermore, works can become permanently inaccessible if the DRM scheme changes or if the service is discontinued. DRM can also restrict users from exercising their legal rights under the copyright law, such as backing up copies of CDs or DVDs (instead having to buy another copy, if it can still be purchased), lending materials out through a library, accessing works in the public domain, or using copyrighted materials for research and education under the fair use doctrine, and under French law. The Electronic Frontier Foundation (EFF) and the Free Software Foundation (FSF) consider the use of DRM systems to be an anti-competitive practice.
what kind of works does it control access to?
restricting the use of proprietary hardware and copyrighted works