A thoroughbred is a breed of horse known for its speed, agility, and endurance, primarily used in horse racing. Originating in the 17th and 18th centuries in England, thoroughbreds are descendants of three foundation sires: Byerley Turk, Darley Arabian, and Godolphin Barb. They are characterized by their slim, athletic build and long legs, making them well-suited for racing. Thoroughbreds are registered with the Jockey Club, which maintains the breed's pedigree and racing records. They are also popular in other equestrian sports, such as show jumping and dressage, due to their intelligence and trainability.