Scientifically, apes are tailless primates native to Africa and South-east Asia. There are two main branches: the gibbons, or lesser apes, which are smaller and are all native to Asia; and the hominids or great apes, including two species of orangutans, two species of gorillas and two species of pan (chimpanzees and bonobos). Scientifically, Humans also fall within the category of great apes, but in the Planet of the Apes franchise humans consider themselves distincts from the chimpanzee, gorilla, and orangutan society collectively referred as apes.
Some iterations of the Planet of the Apes concept have added baboons and mandrills to the core ape society, both of which were once considered species of ape but are now acknowledged to each come from a separate genus of primate which became tailless independently.
In the English language, the term "monkey" refers to tailed primates, and the word is sometimes considered a term of offense by apes within the franchise. In the French language, however, the word 'singes' refers to all primates, and so the original novel La Planète des Singes has been translated as both Monkey Planet and as Planet of the Apes.