Beetles are named for their hardened forewings, which cover the membranous hindwings when not in use for flight. This characteristic is shared by all members of the group, and distinguishes them from most other insects, which have membranous or leathery forewings. Beetles typically have 6 legs (though some may have fewer) and chewing mouthparts. They can be distinguished from other orders by the shape of their antennae. Families within the order Coleoptera have clubbed antennae. Those in other orders may have thread-like or feathery antennae instead.
There are over 350,000 species of beetles, divided into 17 suborders. This number is likely to rise with discoveries still being made today.