Horse races are events in which horses are ridden at high speed over a distance on a paved or dirt track. They are a major sport and an important source of entertainment, often attracting large crowds. Horse racing also involves a significant amount of money and requires considerable skill by the riders, known as jockeys, in order to guide the horse through the tight turns while maintaining control of the animal and maximizing speed. Despite this, horse races can be dangerous for both the animals and their riders. The high speeds at which they are run can cause injuries, including fractures and broken leg bones, and some horses are raced before they are fully mature, increasing the risk of developmental problems such as laminitis.

The first organized horse races in history may have been chariot or mounted (bareback) events at the ancient Olympic Games held between 700-40 bce in Greece. In the early modern period, horse races became more prevalent in Europe and, with their burgeoning popularity came greater demand for better-bred horses and more rules to improve their quality. Rules were developed based on the age, sex, birthplace and past performance of horses, as well as the qualifications of riders. The earliest races were match races between two or three horses, with the owners of each providing the purse and betting on a win or loss. As demand for racing increased, matched races began to be arranged between larger groups of horses. The agreement between the owners to race against each other was recorded by disinterested third parties, who came to be known as keepers of the match book.

In more recent times, the era of horse-racing sophistication has brought about many new types of races, with stakes races offering the largest purses. These include handicap races, in which the fixed weights that horses must carry during a race are adjusted according to their age, or gender, or both, for the sake of fairness. Generally, younger horses and females must carry less weight than males, which gives them a better chance to win.

In addition to handicap races, there are other famous types of horse races such as the Prix de l’Arc de Triomphe in France, the Caulfield Cup in Australia, and the Sydney Cup in New Zealand. In the United States, the Kentucky Derby is perhaps the most famous horse race, with its pageantry, mint juleps, and the large crowd of fans that gather at Churchill Downs.