The hoof is a hard, horny material that partly or completely covers the toes of many mammals. Like nails and claws, hooves develop from the outer layer of the skin. Hooves are also similar to nails and claws because they wear away at the tip and are continually replaced by growth at the base.
All hooved mammals, commonly called ungulates, walk on the tips of their toes. The hooves protect the toes by serving as an insensitive surface to bear the weight of the body. The sharp hooves of many ungulates, including deer and moose, are also used for defense and to scrape away snow from the ground during winter feeding.
Horses, donkeys, and some other ungulates have a single solid hoof on each foot. Related ungulates, such as tapirs and rhinoceroses, have three toes on each foot, and each toe is covered by a separate hoof. In deer, sheep, camels, and antelope, each foot has two toes, each covered by a separate hoof. Since the hooves on each foot are separated by a narrow space, animals whose hooves are divided into two or more parts are commonly called cloven-hooved, which means "divided hoof."