Reining is a western riding competition for horses where the riders guide the horses through a precise pattern of circles, spins, and stops.

It 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.