Horses are a large odd-toed ungulate mammal, one of ten modern species of the genus Equus. They have long been among the most economically important domesticated animals; although their importance has declined with mechanization, they are still found worldwide, fitting into human lives in various ways. The horse is prominent in religion, mythology, and art; it has played an important role in transportation, agriculture, and war; it has additionally served as a source of food, fuel, and clothing.

Almost all breeds of horses can, at least in theory, carry humans on their backs or be harnessed to pull objects such as carts or plows. However, horse breeds were developed to allow horses to be specialized for certain task; lighter horses for racing or riding, heavier horses for farming and other tasks requiring pulling power. In some societies, horses are a source of food, both meat and milk; in others it is taboo to consume them. In industrialized countries horses are predominantly kept for leisure and sporting pursuits, while they are still used as working animals in many other parts of the world.