Reining horses are judges on a series of maneuvers - spinning, circles with change of speed and direction, rollbacks, and the crowd favorite - sliding stops. Reining horses have been bred for generations to be quick yet calm and carry themselves over their hocks while loping, turning, and stopping. Reining began in the United States and is based upon the qualities desired in a good cow horse. Today Reining is enjoyed around the world and is the world's fastest growing equine sport.