Nymphs are characterized as which stage of an insect's life?

Nymphs are indeed characterized as the immature stage of an insect's life cycle. Insects that undergo incomplete metamorphosis, such as grasshoppers and aphids, develop through a series of nymph stages before reaching adulthood. These nymphs often resemble smaller versions of the adult insects, but they have not yet fully developed the characteristics associated with the adult stage, such as wings or reproductive maturity. This distinguishes them clearly from the adult stage, which represents a fully developed insect, from the larval stage, which varies in definition but usually applies to those insects undergoing complete metamorphosis (like caterpillars), and from the egg stage, which is the earliest developmental phase from which nymphs or larvae will eventually emerge.