The American Quarter Horse is an American breed of horse that excels at sprinting short distances. Its name came from its ability to outdistance other breeds of horses in races of a quarter mile or less; some individuals have been clocked at speeds up to 55 mph (88.5 km/h).
The modern Quarter Horse has a small, short, refined head with a straight profile, and a strong, well-muscled body, featuring a broad chest and powerful, rounded hindquarters. They usually stand between 14 and 16 hands high, although some Halter-type and English hunter-type horses may grow as tall as 17 hands.
There are two main body types: the stock type and the hunter or racing type. The stock horse type is shorter, more compact, stocky and well muscled, yet agile. The racing and hunter type Quarter Horses are somewhat taller and smoother muscled than the stock type, more closely resembling the Thoroughbred.