A horse race is a competition in which humans wager on the outcome of a contest involving an animal, usually a horse. Bettors place a wager on one of several types of races, and their winnings are paid out according to the rules of each race.

There are many different rules that govern how a horse race is conducted, including the number of participants, the length of the course, and the minimum age to participate in the race. Some races are open to all, while others have strict eligibility criteria based on the age, sex, and birthplace of the horses, as well as their previous performance.

The earliest horse races were match contests between two, or at most three, horses. As public demand increased, larger fields of runners were produced, and new rules were devised governing the eligibility of horses and the qualifications of their riders. These rules were largely modeled after the British system, where large mature horses are preferred and stamina is considered as important as speed.

Today, most horse racing is dominated by Thoroughbreds, which are large breeds that have been developed in England for the purposes of racing and jumping. Because of the commercial nature of the sport, speed has become the focus of race strategy and breeding programs. The sport is a multibillion-dollar business, and the winners receive substantial prize money that reflects the high stakes involved.

As a result, the majority of the money wagered on horse races comes from gamblers, rather than track owners or stables. This is a major contributing factor to the cruelty and inhumane treatment of horses that occurs on a daily basis throughout the industry. However, the exploitation of horses for their gambling potential has not ended, and the sport continues to grow. In fact, some states have banned betting on horses altogether, while others regulate it through a combination of industry donations and voter approval.

To determine who has won a horse race, the stewards look at photographs of the finish and study them closely to see which horse crossed the line first. If it is impossible to determine the winner, then a dead heat is declared and the bettors’ money will be returned, after a deduction of a percentage by the track. Horses that are deemed to have committed any rule infractions are disqualified. The stewards also take saliva and urine samples from the jockeys to detect prohibited substances. These samples are examined after the races to prevent horse doping, a practice in which horses are injected with cocktails of legal and illegal drugs to enhance their performances. These medications can mask injuries, increase the horse’s stamina, and even alter its heart rhythm. Nevertheless, doping remains an issue in horse racing and has led to the deaths of numerous horses. The practice is so widespread that a recent report by the Jockey Club concluded that it has caused “catastrophic harm” to the sport.