Cutting is an equestrian event in the western riding style where a horse and rider are judged on their ability to separate a calf away from a cattle herd and keep it away for a short period of time. The sport originally evolved from cattle ranches in the American West, where it was the cutting horse's job to separate cows from the herd for vaccinating, castrating, and sorting. Eventually competitions arose between the best cutting horses and riders in the area. Rules were added, and in 1946 the National Cutting Horse Association was formed, which today is the governing body of the sport.

The horses involved are typically Quarter horses, although other breeds may be used, such as American Paint Horses or Appaloosas. A horse that instinctively knows how to keep a calf from returning to the herd, and is trained in a manner to be shown competitively, is considered a cutting horse.

In the event, the horse and rider select and separate a calf out of a small group. The calf then tries to return to its herdmates; the rider loosens the reins ("puts his hand down" in the parlance) and leaves it entirely to the horse to keep the calf separated, a job the best horses do with relish, savvy, and style. A contestant has 2 1/2 minutes to show his horse; typically three cows are cut during a run, although working only two cows is acceptable. A judge awards points to the cutter based on a scale that ranges from 60 to 80, with 70 being considered average.

Cutting is one of the fastest growing equine sports in the world. In 2006, the contestants at the NCHA Futurity competed for more than $3.7 million--over a hundred times the offering of the first year. Total purses at NCHA-approved shows now exceed $39 million annually, not including prize money distributed at Australian Cutting Horse Association and American Cutting Horse Association.