A yak is a large, long-haired, long-horned bovid from the Himalayas. They are heavily built animals with bulky frames, sturdy legs, rounded, cloven hooves, and extremely dense, long fur that hangs down lower than the belly. While wild yaks are generally dark, blackish to brown in coloration, domestic yaks can be quite variable in color, often having patches of rusty brown and cream. They have small ears and wide foreheads, with smooth horns that are generally dark in color. Yaks are high-altitude bovines that graze across the grasslands of the Tibetan Plateau. They have three times the lung capacity of typical cows and can subsist for thousands of years on a meager diet of grasses and sedges. Yak milk is also used to make yogurt and cheese rich in nutritious omega-3 fatty acids, including chhurpi, a hardened yak milk cheese that can be stored for years. In addition to their ecological role, yaks have played an important part in the culture of the Himalayan region. In parts of Tibet and Karakorum, yak racing is a form of entertainment at traditional festivals and is considered an important part of their culture. More recently, sports involving domesticated yaks, such as yak skiing or yak polo, are being marketed as tourist attractions.