A metal mouthpiece attached to a bridle, used to control a horse. The domesticated horse was probably first controlled with a simple halter. Bits, the mouthpiece of a horse's bridle, consisting of a bit-mouth and adjacent parts to which the reins are attached. Bits with cheek-pieces of antler did not appear in central Europe until after 1800 BC and they were later replaced by bronze bits. Bits without a cheek-piece, in 2-piece or 3-piece form, were introduced in the Iron Age.