Horse racing is a sporting activity which has been practiced over the centuries; the chariot races of Roman times were an early example, as was the contest of the steeds of the god Odin and the giant Hrungnir in Norse mythology. It is often inextricably associated with the activity of wagering on the outcome of a race, gambling.

By the time humans began to keep written records, horse racing was an organized sport in all major civilizations from Central Asia to the Mediterranean. Both chariot and mounted horse racing were events in the ancient Greek Olympics by 638 BC, and the sport became a public obsession in the Roman Empire.

The origins of modern horse racing lie in the 12th century, when English knights returned from the Crusades with swift Arab horses. Over the next 400 years, an increasing number of Arab stallions were imported and bred to English mares to produce horses that combined speed and endurance. Matching the fastest of these animals in two-horse races for a private wager became a popular diversion of the nobility.

There are two types of horse racing involving:

Thoroughbred horse racing.
Harness horse racing.

he breeding, training and horse racing in many countries is now a significant economic activity as, to a greater extent, is the gambling industry which is largely supported by it. Exceptional horses can win millions of dollars and make millions more by providing stud services, such as horse breeding. The style of horse racing, the distances and the type of events varies very much by the country in which the race is occurring and many countries offer different types of horse race. There are races which involve obstacles (either hurdles or fences) called steeplechase and those which are unobstructed races over a given distance (flat racing).

Races also can occur on flat surfaces of either dirt or grass, generally Thoroughbred racing; certain tracks also offer Quarter horse racing and harness racing. Horse racing with breeds, such as Arabian horse racing, is found on a limited basis.