Rhinoceros, usually abbreviated as rhinoceros, is one of the five existing ungulates with toes in rhinoceros family and one of the many extinct species. Two of these extant species are native to Africa and three to South Asia.

Members of the rhinoceros family are characterized by their large size (they are part of the largest remaining large fauna, all of which can weigh a ton or more). And through a herbivorous diet; a thick protective skin, 1.5-5 cm thick, formed by a collagen layer positioned in the lattice structure; this size (400-600 g) of the mammalian brain is relatively small; and a large angle. They usually eat leafy materials, although they have the ability to ferment food in their hindgut, allowing them to rely on more fiber plants to survive if necessary. Unlike other trichiosaurs, these two African rhinos have no teeth in front of their mouths and rely on their lips to feed.

Rhinos are killed because their horns are sold on the black market, and some cultures use them for decorative or traditional medical purposes. East Asia, especially Vietnam, is the largest rhino horn market. By weight, rhinoceros horns are priced the same as gold on the black market. People grind horns, then believe that dust has therapeutic effects, and then eat them. The horn is made of keratin, the same type of protein that makes up hair and nails. African species and Sumatran rhinos have two horns, while Indian and Javanese rhinos have only one. The IUCN Red list identifies three critically endangered species.