Digital rights management (DRM) is a generic term that refers to access control technologies used by hardware manufacturers, publishers and copyright holders to limit usage of digital media or devices. Whereas copy protection only attempts to prohibit unauthorized copies of media or files, digital rights management allows the issuer of the media or file to control in detail what can and can not be done with a single instance. For example, an issuer can limit the number of viewings, number of copies, which devices the media can be transferred to etc. Digital rights management often depend on cryptography and on-line activation. Blu-Ray and some recent game titles by Electronic Arts are an example of each. Digital rights management has been and is being used by content provider companies such as Sony, Apple Inc., Microsoft and the BBC.The use of digital rights management is controversial. Advocates argue it is necessary for copyright holders to prevent unauthorized duplication of their work to ensure continued revenue streams.[1] Opponents, such as the Free Software Foundation, maintain that the use of the word "rights" is misleading and suggest that people instead use the term Digital Restrictions Management. Their position is essentially that copyright holders are attempting to restrict use of copyrighted material in ways not covered by existing laws.[2] The Electronic Frontier Foundation, and other opponents, also consider DRM systems to be anti-competitive practices.[3]The term Digital Rights Management has been used by opponents as well.In practice, all widely-used DRM systems have been defeated or circumvented when deployed to enough customers.[4] Restricting copying of audio and visual material is especially difficult due to the existence of the analog hole, and there are even suggestions that effective DRM is logically impossible for this reason.