If you are not familiar WarCraft I or II, they are a Real Time Strategy, RTS, games created by Blizzard Entertainment. RTS games are a fairly new genre started by Westwood Studios, a division of Virgin Interactive, with Dune 2.
Before RTS games were started, strategy games were turn based, like chess. RTS games are far more realistic because in a real war generals do not usually take turns!
WarCraft II is my favorite RTS game, which I spend at least six hours playing a week. WarCraft II can be played with 8 people through the internet or a LAN. Originally players had to pay to play WarCraft over the internet. Kali is the preferred pay server for WarCraft II. Today there are free servers to play at like Heat and the Zone. I usually play on the Zone.
StarCraft has just finished beta testing and hopefully will be in stores soon. The beta testers all claim it is far better then WarCraft II.
Some other RTS games that are out, that I am not so fond of are Age of Empires, Command and Conquer and Total Annihilation. I dislike Age of Empires because of its interface, over complication and graphics. Command and Conquer bored me because all the fighting guys looked the same. Total Annihilation should be commended because it is 3d and does not use sprites. The 3d animation in Total Annihilation, TA, forced it's creators to have only a few simple units. This made TA boring in my opinion.