How do you run Warcraft without the CD?

Warcraft 3 was recently patched to no longer require the CD to start. World of Warcraft as well as The Burning Crusade and Wrath of the Lich King have never required a CD to start.

If earlier versions of Warcraft have not been patched to no longer require the CD, you can download a disc imaging program such as Deamon Tools Lite, create a virtual image of your CD, and "mount" the image to run the game, instead of using the CD.