Horse races are contests where horses compete to win a prize. They can be over a variety of distances, but the most common is a race over a mile. During the early days of horse racing, races were match contests between two or three horses, but pressure from the public eventually produced events that required more skill and stamina. The first horse to reach the finish line is declared the winner.

A number of factors affect the outcome of a horse race, including the size and speed of the competitors, the course design, and the prevailing weather conditions. The most important factor, however, is the ability of a horse to win. To do this, the horse must be able to move forward at a constant rate over the entire course of the race, and it must also be able to keep its pace over a long distance, or several miles. The length of the race varies, depending on the custom of the country in which it is run. In English horse racing, for example, the earliest races were over 21/2-mile (4-kilometer) courses, while more modern American races are often only one-mile (1.6 kilometers).

Historically, horse races have been held in many different countries and cultures. Archeological records show that it was a popular sport in Ancient Greece, Ancient Rome, and Babylon, among other places. It is also mentioned in literature and mythology, such as the contest between Odin and the giant Hrungnir in Norse legend.

Behind the romanticized facade of Thoroughbred horse racing is a world of drugs, injuries and gruesome breakdowns. The animals are forced to sprint-often under the threat of whips and illegal electric shock devices-at speeds that make them susceptible to a variety of injuries and even pulmonary hemorrhage. The death of Eight Belles, a filly that was forced to the finish line in 2008 after being doped with a cocktail of legal and illegal drugs, brought attention to this hidden side of the industry. The true number of horses that die on the track is unknown, as California and New York maintain public databases but Kentucky does not.

Before a race, the horses are led into the starting gate, which is electrically operated at most tracks. As the start goes off, stewards and patrol judges, aided by a camera-mounted surveillance system, look for rule infractions. Saliva and urine samples are taken from the horses to check for the presence of prohibited substances. Jockeys must weigh in to ensure that they are carrying the right amount of weight, and jockeys may claim penalty points if they are found to have violated rules during the race.

Proponents of the horse race approach to succession management say that it is a powerful tool for selecting the most effective senior leader from among several capable executives. They contend that an overt competition for the CEO role encourages the board and current leadership to develop strong internal candidates through a series of functional assignments and stretch opportunities, and that it will lead to a stronger company in the end.