The orangutans (also spelled orang-utan, orangutang, or orang-utang)[1] are the two exclusively Asian species of extant great apes. Native to Indonesia and Malaysia, orangutans are currently found in only the rainforests of Borneo and Sumatra. Classified in the genus Pongo, orangutans were considered to be one species. Since 1996, they have been divided into two species: the Bornean orangutan (P. pygmaeus) and the Sumatran orangutan (P. abelii). In addition, the Bornean species is divided into three subspecies.

Based on genome sequencing, the two extant orangutan species evidently diverged around 400,000 years ago. The orangutans are also the only surviving species of the subfamily Ponginae, which also included several other species, such as the three extinct species of the genus Gigantopithecus, including the largest known primate Gigantopithecus blacki. The ancestors of the Ponginae subfamily split from the main ape line in Africa 16 to 19 million years ago (mya) and spread into Asia.