What exactly is DRM in lehmanns terms?
Is it like copy protection?
Its essentially the same thing, just newer and scarier sounding.
The main forms of DRM around at the moment are a few versions of SecuROM, some of which have limited installs, and once you use them up, you have to phone the publisher and ask for more installs.
Ubisoft have their own DRM which requires you to be connected to their servers in order to play their games, and if the connection goes down, it used to be that the game would pause, and wouldn't continue until the connection reestablished, though I dont' know if this has changed or not.
Tages is occasionally used, though I'm not too sure on its details.
Steam is also a form of DRM, as you have to buy the game thorugh Steam and run Steam to play the games, however this is generally agreed on as an acceptable form of DRM because it works so well, while the others mentioned above have several flaws that make things harder for people who legally buy the game, having restrictions such as install limits or requiring an internet connection to play, while people who pirate the games have no such restrictions, though with some systems, especially Ubi's current one, there are significant time delays between a game being released, and a working pirated version making its way onto the internet.