DRM in one paragraph

Cory just posted over at Boing Boing the best brief description of DRM that I’ve read so far:

DRM -- Digital Rights Management, or Digital Restrictions Management -- is technology that prevents you from using some files by taking over part of your computer so that it won't obey your requests. DRM is always proprietary. Before a DRM is released, it is infected with "Hook IP" -- a patent or trade secret that is introduced to the technology so that the only way you can implement the DRM is by licensing the Hook IP. Anyone who licenses the Hook IP is forced to promise to make their DRM behave as intended, preventing uses and taking over computers and devices. Without Hook IP, a company could implement the DRM but leave out the restrictions, shipping products that allow all the uses their competitors' products deny. Hook IP gives the DRM maker something to sue over if this happens.