Public domain picture from U.S. Fish and Wildlife Service full size image
The elephant is the heaviest living land animal. Its most typical characteristic is the trunk, a very much elongated nose, which can be used to grab objects, such as food. Elephants also have tusks, large teeth coming out of their upper jaws. Elephants tusks are the major source of ivory, but because of the increased rarity of elephants, almost all hunting and trade is now illegal.
African and Indian elephants are separate species, Loxodonta africana and Elephas maximus. The African elephant has two populations, savannah and forest, and recent genetic studies have led to a classification of these as separate species, Loxodonta cyclotis. (See http://www.education.guardian.co.uk/Print/0,3858,4244642,00.html) This work has important implications for conservation, because it means there are two species that need protection, and fewer of each species. There's also a potential danger in that the forest elephant isn't explicitly listed as an endangered species, and poachers and smugglers might thus be able to evade the law forbidding trade in endangered animals and their body parts.
Elephants have been used in various capacities by humans. In Siam and India they were used in the military, and have been used for transportation and entertainment, as in American circuses. The Carthaginian general Hannibal attempted to take elephants across the Alps when he was fighting the Romans, with little success. However, elephants have never been truly domesticated: the male elephant in heat is dangerous and difficult to control, such that elephants used by humans have typically been female.
In the wild, elephants exhibit complex social behavior and strong family bonds.
See also: Proboscidea