Buffalo, a name properly pertaining to an aberrant species of cattle which has been kept in a state of domestication in India and Egypt from time immemorial, and had been introduced from the latter country into southern Europe. It is now taken, however, to include not only this species, whose native home is India, but all more or less nearly related animals. Buffaloes are heavily built oxen, with sparsely haired skin, large ears, long, tufted tails, broad muzzles and massive angulated horns. In having only 13 pairs of ribs they resemble the typical oxen. African buffaloes all have the hair of the back directed backwards.
In the Cape buffalo, Bos (Bubalus) caffer, the horns do not attain an excessive length, but in old bulls are so expanded and thickened at the base as to form a helmet-like mass protecting the whole forehead. Several more or less nearly allied local races have been named; and in Eastern Africa the buffaloes (B. caffer aequinoctialis) have smaller horns, which do not meet in the middle line. From this animal, which is brown instead of black, there seems to be a transition towards the red dwarf buffalo (B. nanus) of West Africa, an animal scarcely more than two-thirds the size of its gigantic southern cousin, with relatively small, much flattened, upwardly curved horns. In South Africa buffaloes frequent reedy swamps, where they associate in herds of from fifty to a hundred or more individuals. Old bulls may be met with either alone or in small parties of from two or three to eight or ten. This buffalo formerly roamed in herds over the plains of Central and Southern Africa, always in the near vicinity of water, but the numbers are greatly diminished. In Cape Colony some herds are protected by the government in the eastern forest-districts. This species has never been domesticated, nor does there appear to have been any attempt to reduce it to service.
Like its Indian ally it is fond of water, which it visits at regular intervals during the twenty-four hours; it also plasters itself with mud, which, when hardened by the sun, protects it from the bite of the gadflies which in spite of its thick hide seem to cause it considerable annoyance. It is relieved of a portion of the parasitic ticks, so common on the hides of thick-skinned animals, by means of the red-beaked rhinoceros birds, Buphaga erythrorhynca, a dozen or more of which may be seen partly perched on its horns and partly moving about on its back, and picking up the ticks on which they feed. The hunter is often guided by these birds in his search for the buffalo, but oftener still they give timely warning to their host of the dangerous proximity of the hunter, and have thus earned the title of "the buffalo's guardian birds."
In a wild state the typical Indian buffalo, Bos (Bubalus) bubalis, seems to be restricted to India and Ceylon, although some of the buffaloes found in the Malay Peninsula and Islands probably represent local races. The species has been introduced into Asia Minor, Egypt, Italy and elsewhere. The large size and wide separation of the horns, as well as the less thickly fringed ears, and the more elongated and narrow head, form marked points of distinction between the Asiatic and South African species. Moreover, all Asiatic buffaloes are distinguished from the African forms by having the hair on the fore-part of the back directed forwards; and these go far to support the views of those who would make them the types of a distinct subgenus, or genus, Buffelus. In Assam there formerly existed a local race, B. bubalis macrocercus, characterized by the horns, which are of immense size, being directed mainly outwards, instead of curving upwards in a circular form. Another Assam race (B. bubalis fulvus) is characterized by the tawny, in place of black, colour of its hair and hide. The haunts of the Indian buffalo are the grass-jungles near swamps, in which the grass exceeds 20 ft. in height.
Here the buffaloes - like the Indian rhinoceros - form covered pathways, in which they are completely concealed. The herds frequently include fifty or more individuals. These animals are fond of passing the day in marshes, where they love to wallow in the mud; they are by no means shy, and do much harm to the crops. The rutting-season occurs in autumn, when several females follow a single male, forming for the time a small herd. The period of gestation lasts for ten months, and the female produces one or two calves at a birth. The bull is capable, it is said, of overthrowing an elephant, and generally more than a match even for the tiger, which usually declines the combat when not impelled by hunger. The Indian driver of a herd of tame buffaloes does not shrink from entering a tiger-frequented jungle, his cattle, with their massive horns, making short work of any tiger that may come in their way. Buffalo fights and fights between buffaloes and tigers were recognized Indian sports in the old days. Domesticated buffaloes differ from their wild brethren merely by their inferior size and smaller horns; some of the latter being of the circular and others of the straight type.
The milk is good and nourishing, but of a ropy consistency and a peculiar flavour.
The tamarao, or Philippine buffalo, Bos (Bubalus) mindorensis, is a smaller animal, in many respects intermediate between the Indian buffalo and the dwarf anoa, or Celebes buffalo (B. depressicornis).
 In America, it is worth noting, the term "buffalo" is almost universally taken, at all events in popular parlance, to designate the American bison, for which see Bison.