A monkey is any member of the infraorder Similformes of the order Primates that does not belong to the great apes or humans. Monkeys have well-developed brains and hands that are freed for manipulative activities; however, their cognitive abilities do not reach those of the great apes. Some species, such as the capuchins, spontaneously use objects as tools; others, like baboons, must learn to do so.
Monkeys usually live in groups called troops, and they form close bonds with each other. The troops are led by one or more males and include a mix of young and adult females and their offspring, or all adult females (in the case of hamadryas baboons and most mandrills). Some monkeys have prehensile tails that they can use to grasp branches, but this is not true for all species.
They eat fruit, seeds, leaves, nuts, flowers, insects and small animals such as bats. They are skilled at climbing and can traverse the most rugged terrain. They may also eat roots, seeds and bark to supplement their diet.
In the wild, monkeys travel a lot to find food. In their search, they often spread the seeds of plants and flowers along the way. For this reason, introducing new species of monkeys to places where they do not naturally occur can disrupt the balance of the ecosystem.