By WALTER S. MOSSBERG
In some quarters of the Internet, the three most hated letters of the alphabet are DRM. They stand for Digital Rights Management, a set of technologies for limiting how people can use the music and video files they've purchased from legal downloading services. DRM is even being used to limit what you can do with the music you buy on physical CDs, or the TV shows you record with a TiVo or other digital video recorder.
Once mainly known inside the media industries and among activists who follow copyright issues, DRM is gradually becoming familiar to average consumers, who are increasingly bumping up against its limitations.
DRM is computer code that can be embedded in music and video files to dictate how these files are used. The best-known example is the music Apple Computer sells at its iTunes Music Store. Using a DRM system it invented called FairPlay, Apple has rigged its songs, at the insistence of the record companies, so that they can be played only on a maximum of five computers, and so that you can burn only seven CDs containing the same playlist of purchased tracks. If Apple hadn't done this, the record labels wouldn't have allowed it to sell their music.
DRM systems are empty vessels -- they can enforce any rules copyright holders choose, or no rules at all. Apple's DRM rules are liberal enough that few consumers object to them. In fact, obtaining relatively liberal DRM rules from the labels was the key to Apple's success in selling music. But some other uses of DRM technology aren't so benign.