The forehead is high and the muzzle bulges. There is little of the brow ridge evident in the other great apes. Cheek pads are present in adults and may be quite large in older males. The small ears are devoid of hair. The legs are relatively short and weak while the arms are long and powerful.
Orangutans are primarily diurnal and arboreal.
While not as social as other apes, they may congregate when fruit is abundant. They use vegetation to construct nests for sleeping, which are usually only used once. Smaller nests may be made for daytime rests. Orangutans use leafy branches held over their heads or large leaves draped over their head and shoulders as protection from both rain and sun. Tool use among fully wild orangutans does not compare with that of chimpanzees, though captive orangutans released into the wild are quite adept at tool use.