In the hacker underground, the term "warez" ('wares == softwares) refers to illegally copied programs. Because of the illegal nature of this activity, it is a constantly shifting/moving "scene" rather than an established activity.
The "warez" scene is tightly knit with the other anarchy elements that deal with file transfers. Therefore, you often see warez together with porn and MP3; file archives that deal with one often deal with the others as well.
