Monkeys are mammals and come from the order of primates. This word comes from the Latin word "primus" and means "the first". Monkeys are the closest animal relatives of humans. One of the characteristics of this order is a more highly developed brain. Monkeys are also most similar to humans in appearance.
Monkeys are smart and sociable animals. They mostly feed on plants, but sometimes they also take insects. Some monkeys can walk on two legs, like a human. Others walk on all fours all the time.
When we speak of apes today, we often mean a term from colloquial language or from our everyday speech. For example, we know the gorillas, usually from the zoo. Then we refer to all animals that are similar as apes. In the science of biology, however, it is much more complicated.