Horse racing is a sport in which people wager on the outcome of a race between two or more horses. It has a long history and was practiced by the ancient Greeks, Romans, Babylonians, and others. In the Middle Ages, it was popular in Europe. It is also an important part of myth and legend, such as the contest between Odin’s steeds in Norse mythology. Modern horse races are run over distances of between 440 yards (400 meters) and four miles (6 kilometers). Individual flat races may be referred to as sprints or routes, depending on the custom of the country in which they are held. Speed is emphasized in American races, while stamina is a factor in European racing.

The earliest horse races were match contests between two or three horses, but pressure by the public led to open events with larger fields of runners. Rules were developed to determine eligibility for races based on the age, sex, birthplace, and previous performance of horses, as well as the qualifications of jockeys. Saliva and urine samples are also tested for prohibited substances.

For a period of time, doping in horse racing was widespread, but it is not considered as severe today as it was then. Drugs such as cocaine, heroin, and strychnine were used by jockeys to increase their horses’ endurance. The use of such substances was regulated by the British Jockey Club. Eventually, the practice of using drugs to improve a horse’s performance became known as “blood doping.”

Currently, horses are injected with anabolic steroids and growth hormones before they are raced. The medications are designed to make the horse grow taller, and to make the muscle more dense. They can also help a horse recover faster from the intense exertion of a race, and to increase its speed. Many jockeys believe that these drugs are a major reason why horse races have become so dangerous for the animals.

In the past, racehorses were owned by wealthy individuals or large syndicates. In the past few decades, it has become more common for horses to be owned by a group of investors, often called a stable. Some examples are the 2005 Epsom Derby winner Motivator, who was owned by the Royal Ascot Racing Club, and 2008 Kentucky Derby winner Big Brown, who was owned by IEAH Stables, a hedge fund organization.

The practice of betting on horse races has fueled controversy. Some groups, including animal rights activists and some politicians, argue that horse racing is not a legitimate sport because it causes horses to be drugged and abused. According to the activist group Horseracing Wrongs, ten thousand American thoroughbreds are killed each year for racing purposes, and those who survive live in solitary confinement in a barn. Others point to studies that show that probabilistic polling discourages voting, by fostering cynicism among young voters about politics. The research, by political scientists, was published in the journal FiveThirtyEight and featured in The New York Times and Huffington Post.