Orangutans are a genus (Pongo) of great apes consisting of two species, the Sumatran orangutan (Pongo abelii), and the Borneo orangutan (Pongo pygmaeus).

The other genus of great apes are Homo (one species, Homo sapiens, man), found globally, Gorilla (two species, found in Africa), Pan (the chimpanzee and bonobo, found in Africa).

The orangutan is therefore the only great ape found exclusively in Asia, specifically in Sumatra and Borneo.

Orangutans, while closely related to humans, were the first to diverge from the great ape family, around fourteen million years ago, and are hence less closely related to humans than are the other great ape species. Orangutan share around 97% DNA similarity with humans.

Orangutans, like other apes and monkeys, had ancestors which lived in Africa, although they have migrated there from Europe or Asia. Some of these ancestors moved into  Asia, where fossils of extinct species such as Sivapithecus have been found. Sivapithecus lived around 12 million years ago in South Asia, and has similarities with orangutans and with chimpanzees.