A dragonfly is a flying insect belonging to the order Odonata, infraorder Anisoptera (from Greek ἄνισος anisos, "unequal" and πτερόν pteron, "wing", because the hindwing is broader than the forewing). Adult dragonflies are characterized by a pair of large, multifaceted compound eyes, two pairs of strong, transparent wings, sometimes with coloured patches, and an elongated body. Dragonflies can be mistaken for the closely related damselflies, which make up the other odonatan infraorder (Zygoptera) and are similar in body plan though usually lighter in build; however, the wings of most dragonflies are held flat and away from the body, while damselflies hold their wings folded at rest, along or above the abdomen. Dragonflies are agile fliers, while damselflies have a weaker, fluttery flight. Many dragonflies have brilliant iridescent or metallic colours produced by structural colouration, making them conspicuous in flight.