Drunk brakes are generaly found on the rear wheels of older (or cheaper) cars. They are inferior to disc brakes as heat cannot escape as effectively while heavy braking can also cause the drums to quickly ware out. In drum brakes friction is caused by a set of pads which press against the inner surface of a rotating drum which is connected to a rotating wheel. However they are still in use today as they are cheaper to manufacturer are found on cheaper (Korean) cars sold here in Australia. It is good advice to try to purchase a vehicle with Disc Brakes instead.