FACTBOX - Key details on Digital Rights Management

LONDON (Reuters) - Five facts about Digital Rights Management (DRM) after EMI Group said it would make all of its digital repertoire available without the anti-piracy software.

* DRM is software which entertainment companies use to prevent illegal copying or distribution of digital media files such as songs and movies.

* Apple's proprietary Fairplay protection technology is one of the most commonly used to protect songs, TV shows and movies. Microsoft Corp. has its own Windows Media-based protection technology.

* DRM protection of a song or movie can be used to prevent it from playing on a non-compatible digital media player or software. For example, Apple's Fairplay format will only work within Apple's iPod player and iTunes system.

* The most popular digital song format, an unprotected MP3, does not have any DRM protection.

* More than 1 billion digital songs in MP3 format are traded illegally every month on peer-to-peer networks such as Limewire, according to Web consultants Big Champagne.