Yak, an ox of China and India. The yak lives at altitudes of 13,000 to 20,000 feet (3,960 to 6,100 m). It feeds on sparse grasses, herbs, and lichens. There are both wild and domesticated yaks. The wild yak is brownish-black with a rounded hump and horns that curve upward and forward. The bull is about six feet (1.8 m) tall at the shoulder and weighs about 1,200 pounds (540 kg). The female is smaller. Long hairs grow over the eyes and cover most of the body. The tail has a thick tassel of long hair. Due to indiscriminate hunting, the wild yak is endangered.

The domestic yak is somewhat smaller, has shorter horns, and is red, brown, black, or mottled. It is used for plowing, as a pack and saddle animal, and as a source of meat and milk, which is used to make cheese and butter. The hair is used to make clothing, rope, and tent covers.

The yak is Bos grunniens, or B. mutus, of the family Bovidae.