Digital Rights Management (DRM)
DRM is basically a set of technologies used by publishers or copyright owners to control access to and usage of digital data or hardware, and to restrictions associated with a specific instance of a digital work or device. (Taken from Wikipedia)

 

Most popular DRM tecnologies

Tecnology Usage Related links
The Content Scrambling System (CSS) DVD protection CSS a Technical Description
Cryptanalysis of Contents Scrambling System
CSS (Wikipedia)
Gallery of CSS Descramblers
Advanced Access Content System (AACS) HD DVD and Blu Ray disc protection AACS Specifications
AACS Decryption Code Released
Understanding AACS
Apple FairPlay iTunes Store, iPod How FairPlay Works
FairPlay protection remover
Windows Media DRM Online stores like Napster, AOL Music Now and others. Tutorials from Microsoft
Protection remover forum
Microsoft and FairUse4WM
WMA Convert Software
Extended Copy Protection (Better known as the Sony rootkit) Sony and BMG CDs Extended Copy Protection
XCP remove instructions
Real Story of the Rogue Rootkit
Mark Russinovich's Blog
Others DRM Technologies
Tecnology Usage
Microsoft 3-day-3-play Microsoft Zune
OMA DRM Used in cell phones to protect ring tones.
Content Protection for Recordable Media CPRM / CPPM Secure Digital cards.
High-bandwidth Digital Content Protection (HDCP) HD DVD, Blu-ray Disc and DVD players (with HDMI or DVI connector) use HDCP to establish an encrypted digital connection.
Easy Bits DRM Skype PlugIn Manager
Adobe eBooks DRM (eBox) eBooks in PDF format.