Reins consist of leather straps or rope attached to the outer ends of a bit and extend to the rider's or driver's hands. Reins are the means by which a horse rider or driver communicates directional commands to the horse's head. Pulling on the reins can be used to steer or stop the horse. The sides of a horse's mouth are sensitive, so pulling on the reins pulls the bit, which then pulls the horse's head from side to side, which is how the horse is controlled.Price, Steven D. (ed.) The Whole Horse Catalog: Revised and Updated New York:Fireside 1998 p. 159-161
