Scarabs are stout-bodied beetles, many with bright metallic colours, measuring between 1.5 and 160 mm. They have distinctive, clubbed antennae composed of plates called lamellae that can be compressed into a ball or fanned out like leaves to sense odours. Many species are fossorial, with legs adapted for digging. In some groups males (and sometimes females) have prominent horns on the head and/or pronotum to fight over mates or resources.

The C-shaped larvae, called grubs, are pale yellow or white. Most adult beetles are nocturnal, although the flower chafers (Cetoniinae) and many leaf chafers (Rutelinae) are active during the day. The grubs mostly live underground or under debris, so are not exposed to sunlight. Many scarabs are scavengers that recycle dung, carrion, or decaying plant material. Others, such as the Japanese beetle, are plant-eaters.

Some of the well-known beetles from the Scarabaeidae are Japanese beetles, dung beetles, June beetles, rose chafers (Australian, European, and North American), rhinoceros beetles, Hercules beetles and Goliath beetles.

Several members of this family have structurally coloured shells which act as left-handed circular polarisers; this was the first-discovered example of circular polarization in nature.

In Ancient Egypt, the dung beetle now known as Scarabaeus sacer (formerly Ateuchus sacer) was revered as sacred. Egyptian amulets representing the sacred scarab beetles were traded throughout the Mediterranean world.