The bit is an item of a horse's tack. It usually refers to the assembly of components that contacts and controls the horse's mouth, and includes the shanks, rings, cheekpads and mullen, all described here below, but it also sometimes simply refers to the mullen, the piece that fits inside the horse's mouth. The mullen extends across the horse's mouth and rests on the bars, the region between the incisors and molars where there are no teeth. The bit is located on the horse's head by the headstall, and which has itself several components to allow the most comfortable adjustment of bit location and control.
A horse wearing an English bridle with a snaffle bit, the end of which can be seen just sticking out of the mouth. The bit is not the metal ring.
Horse skull showing the large gap between the front teeth and the back teeth. The bit sits in this gap, and extends beyond from side to side.
A Luristan bronze horse bit
The bits of a double bridle, showing both a type of snaffle bit called a bradoon and a curb bit
Tack is equipment or accessories equipped on horses and other equines in the course of their use as domesticated animals. This equipment includes such items as saddles, stirrups, bridles, halters, reins, bits, and harnesses. Equipping a horse is often referred to as tacking up, and involves putting the tack equipment on the horse. A room to store such equipment, usually near or in a stable, is a tack room.
A horse equipped with a saddle for mounted police.
A nylon halter/headcollar
A bosal hackamore
A pelham bit with a jointed mouthpiece