Digital rights management (DRM) is a generic term for access control technologies that can be used by hardware manufacturers, publishers, copyright holders and individuals to try to impose limitations on the usage of digital content and devices.
It is also, sometimes, disparagingly described as Digital Restrictions Management. The term is used to describe any technology which inhibits uses (legitimate or otherwise) of digital content that were not desired or foreseen by the content provider. The term generally doesn't refer to other forms of copy protection which can be circumvented without modifying the file or device, such as serial numbers or key files.
It can also refer to restrictions associated with specific instances of digital works or devices. Digital rights management is being used by companies such as Sony, Apple Inc., Microsoft, AOL and the BBC.
The use of digital rights management is controversial. Proponents argue it is needed by copyright holders to prevent unauthorized duplication of their work, either to maintain artistic integrity or to ensure continued revenue streams.
You know, DRM limits the amounts of the players. only can be playable on 5 players. So unfair. What's more, iTunes DRM makes you play only on the players Apple Inc. produced.
When you convert the iTunes movies rentals, the converted files can be played freely. There is no limitations of the amount of the players, and also you can play the common players, like MP4, iriver and so on.
Digital rights management systems have received some international legal backing by implementation of the 1996 WIPO Copyright Treaty (WCT). Article 11 of the Treaty requires nations party to the treaties to enact laws against DRM circumvention. But there are also kinds of DRM oppositions. Many organizations, prominent individuals, and computer scientists are opposed to DRM.
To meet most of people's "DRM-free" thought, there come out many methods to bypass DRM control on audio and video content. Many software programs have been developed that intercept the data stream as it is decrypted out of the DRM-restricted file, and then use this data to construct a DRM-free file.