All insects have three pairs of jointed legs. Six jointed legs are one of the defining characteristics of insects, in addition to a three-segmented body, a hard exoskeleton, one pair of antennae and compound eyes.
Insects belong to the class Insecta and are the largest group of arthropods on earth, with as many as 10 million living species estimated. The life cycle of an insect is divided in separate stages. Insects that experience complete metamorphosis begin as eggs, hatch as larvae and become pupae before emerging as adults. Those that undergo incomplete metamorphosis lack the pupal stage and instead emerge as nymphs from eggs, or miniature versions of their adult forms.