PlayReady

PlayReady is a media file copy prevention technology from Microsoft that includes encryption, output prevention and digital rights management (DRM). It was announced in February 2007.
Technological Differences.
The main differences relative to previous DRM schemes from Microsoft are:
Competitors.
PlayReady competes with other proprietary DRM schemes and even more with DRM-free software, most notably Apple's FairPlay introduced in iTunes and QuickTime. There are several other DRM schemes that are competing to become the dominant DRM technology (e.g. Widevine).
Versions.
Microsoft released the first version of the PlayReady suite (Porting Kit for devices, PC SDK and runtime, Server SDK) in June 2008. Silverlight 2.0, released in October 2008, supports content restricted with PlayReady. As of Silverlight 4.0, the implementation of Microsoft PlayReady in Silverlight supports offline content (via persisted license), subscription scenarios (via chained licenses) and online, streaming-only content (via simple non-persistent licenses). Output protection support was also added in Silverlight 4.0.