The Asteroid Belt is the region of the solar system where Asteroids orbit, between Mars and Jupiter. The term is also used in a more general sense for regions of the solar system with smaller populations of similar bodies, so the "traditional" asteroid belt may be called the Main Asteroid Belt or Main Belt and an asteroid in them a Main Belt Asteroid (MBA).
Among the other asteroid populations (called Asteroid Families):
Kuiper Belt (K Belt)
Late Heavy Bombardment (LHB)