Digital Right Management. The result of an increasing, if not unfounded, fear in a digital age of media piracy and how it could ruin the music and gaming industries. It's basically anything which prevents you, the consumer, from pirating digital content. For example, if you try tampering with your
Xbox 360 to play pirated games then the guys down at Microsoft know what you're doing and can shut the console off permanently. Some forms work well and are met with general approval (iTunes, Steam) and others not so much (SecuROM).
Much of the discontent for DRM comes from a liberal-minded consumer base that insists if you bought it, you own it. But
unfortunately nowadays you don't really own digital media anymore, you only own the rights to use it. For example, if one were to read the Terms of Use, it is clearly written out that you don't actually own the game but only the license for it. This is particularly prevalent in
online games, where patches, expansions, and DLC are always
changing the game and developers reserve the right to remove this content at their leisure.