The various species are adapted to the different terrains they inhabit. Arboreal species are slim, delicate, and have a long tail, while terrestrial species are stockier and their tails can be small or completely nonexistent. All species have well-developed thumbs. Some species have ischial callosities on their rump, which can change their colour during their mating periods.
These monkeys are diurnal and live together in social groups. They live in all types of terrain and climate, from rain forests, savannah, and bald rocky areas, to cool or even snowy mountains, such as the Japanese macaque.
Most species are omnivorous, with diets ranging from fruits, leaves, seeds, buds, and mushrooms to insects, spiders, and smaller vertebrates. All species possess cheek pouches in which they can store food.
Gestation lasts around six to seven months. Young are weaned after three to 12 months and are fully mature within three to five years. The life expectancy of some species can be as long as 50 years.