Also called the lesser apes, gibbons differ from great apes (chimpanzees, gorillas, orangutans and humans) in being smaller and pair-bonded, in not making nests, and in certain anatomical details in which they superficially more closely resemble monkeys than great apes do. Gibbons are masters of their primary mode of locomotion, brachiation, swinging from branch to branch for distances of up to 15 m (50 ft), at speeds as high as 56 km/h (35 mph). They can also make leaps of up to 8 m (27 ft), and walk bipedally with their arms raised for balance. They are the fastest and most agile of all tree-dwelling, non-flying mammals.

Depending on species and gender, gibbons' fur coloration varies from dark to light brown shades, and anywhere in between black and white. It is rare to see a completely white gibbon.

Photo: Detail from Yi-Yuanji: Two gibbons in an oak tree