Many of the top marching musicians of a region participating in an event similar to marching band, but different in the fact that it uses only brass and percussion instruments. Woodwinds (clarinets, flutes, saxophones, etc) are excluded from drum corps. Akin to marching band on steroids, and providing an unforgettable and powerfull experiance to it's members.
Examples of drum corps:
Santa Clara Vanguard