Bos taurus or taurine cattle were bred to survive in the cold climates of the Northern hemisphere. They are the typical type of cows that are viewed on farms and dairies and are cultivated primarily for their beef or for milk and milk products. Taurine cattle can differ widely in their looks. Beef cattle such as Texas longhorn breed have massive horns that can measure up to 5 feet across and look threatening while the tan-colored Jersey milk cows are hornless and harmless-looking.
Zebu are domesticated cattle that are adapted to hot climates. The Brahmin cow from India with its characteristic hump is an example of Zebu cattle. Zebu are quite distinct from taurine cattle in their looks--they sport a fatty hump and a long dewlap, which is a flap of skin that hangs beneath the cow's neck. Zebu cattle are also used for milk and beef as well as for labor. Their dung is used for fuel.
Once, there were 12 species of wild cattle in the world. Today, only 10 of those species survive and in small pockets. According to Wild Cattle Conservation, a website devoted to helping conserve these species, wild cattle are characterized by "a slow growth rate, delayed maturity and low fecundity" or fertility which makes it even more difficult for them to survive when threatened by poaching and encroachment of humans on their habitat. Examples of wild cattle are the American bison and the wild water buffalo from Asia.
Wild and domesticated cattle are sometimes bred together to create new varieties or breeds of cattle. In Nepal, the Dwarf Lulu cow was developed by breeding local cows with Tibetan wild oxen. In North America the Beefalo cattle genes were mixed with the American bison. Some hybrids are infertile such as the Nepalese Dzo which are a cattle/yak mix. Since these cattle are specifically bred to work in fields, new Dzo have to be created when required.