There are two main groups of monkeys. Those which live in South America all live in the tree-tops. They are wonderful climbers, and many have prehensile (gripping) tails which they use as an extra hand. The others are found in Africa and the warm parts of Asia. None of these has a prehensile tail, and they are much more varied in their life-styles. Some, like baboons, live mainly on the ground. Others, such as the guenons, live in the trees, but they run along big branches and do not swing with their arms. Some, like the colobus monkeys, rarely leave the tree-tops. They are expert climbers and swing hand over hand from quite small branches.

When they are resting, all of the African and Asian monkeys sit upright. They have areas of hardened skin, called callosities or sitting patches, on their buttocks, which act a bit like built-in cushions. Almost all monkeys live in a territory which they defend from others of their own kind. Within the group each monkey known its place, and the leader is rarely challenged. There may be noisy arguments, but the fighters are hardly ever seriously damaged.