A hoof is the hard, thick covering on the foot of certain animals, like horses, deer, goats, and pigs. Think of it as nature's version of a sturdy boot: tough enough to protect the animal's foot as it runs, climbs, or walks across rocks, dirt, and rough ground.

Hooves (the plural of hoof) are made of keratin, the same material as your fingernails, but much thicker and stronger. A horse's hoof can support its entire weight as it gallops at high speeds. Wild horses naturally wear down their hooves by traveling many miles each day, but domestic horses need a farrier (a professional hoof specialist) to trim and care for their hooves regularly, similar to how you might clip your nails.

Animals with hooves are called ungulates. Some, like horses and zebras, have a single hoof on each foot. Others, like deer and cattle, have cloven hooves that split into two parts, like wearing shoes with a seam down the middle. These different hoof types help animals move through different terrains: solid hooves work well for running on plains, while split hooves give better grip on rocky, mountainous ground.