Orcs are one of the races in Games Workshop's Warhammer Fantasy universe, and are related to goblins. The brutish orcs, though less intelligent, tend to dominate the meeker goblins. In Warhammer Fantasy Battle, rules for using orcs are covered in the book Warhammer Armies: Orcs & Goblins.
Orcs in Warhammer are not very intelligent or knowledgeable but are capable of cunning. In combat they can transform even the most common object into a lethal killing instrument. They are extremely warlike, with a society geared towards constant warfare, living in small tribal groups with a strong chain of command. They are known for large, brutal armies of difficult-to-kill troops, usually supported by a variety of units and war machines. The constant need to fight keeps the orcs from forming anything but temporary alliances with one other. This is described in-game as "animosity".