Reining is a western riding competition for horses where the riders guide the horses through a precise pattern of circles, spins, and stops. All work is done at the lope (a version of the horse gait more commonly known worldwide as the canter), or the gallop (the fastest of the horse gaits). Originating from working cattle, reining is often described as a Western form of dressage riding, as it requires the horse to be responsive and in tune with its rider, whose aids should not be easily seen, and judges the horse on its ability to perform a set pattern of movements. The horse should be willingly guided or controlled with little or no apparent resistance and dictated to completely. A horse that pins his ears, conveying a threat to his rider, refuses to go forward, runs sideways, bounces his rear, wrings his tail in irritation or displays an overall poor attitude is not being guided willingly, and is judged accordingly.

Sliding Stop: the horse accelerates to a gallop and then suddenly comes to a complete halt, planting its hind feet in the footing and allowing its hind feet to slide several feet, while continuing to let its front feet "walk" forward. The back should be raised upward and hindquarters come well underneath. A particularly powerful stop may, depending on arena conditions, produce flying dirt and a cloud of dust. The movement should finish in a straight line, and the horse's position should not change.