The wrens are passerine birds in the mainly New World family Troglodytidae. There are about 80 species of true wrens in about 20 genera, though the name is also ascribed to other unrelated birds throughout the world. Only one species occurs in the Old World, where it is commonly known simply as the "Wren"; it is called Winter Wren in North America.
The 27 Australasian "wren" species in the family Maluridae are unrelated, as are the New Zealand wrens in the family Acanthisittidae, the antwrens in the family Thamnophilidae, and the wren-babblers of the family Timaliidae.
Troglodyte means "cave-dweller", and the wrens get their scientific name from the tendency of some species to forage in dark crevices. They are mainly small and inconspicuous, except for their loud and often complex songs. These birds have short wings and a thin down-turned bill. Several species often hold their tails upright. All are insectivorous, though some also feed on vegetable matter, and the larger—sometimes notably bold—species in of the genus Campylorhynchus will take small vertebrates (e.g. lizards).
They range in size from the White-bellied Wren, which averages under 10 centimetres (4 in) and , to the Giant Wren, which averages about 22 cm (9 in) and 50 g (2 oz). The dominating colours are grey, brown, black and white, and most species show some barring, especially to tail and/or wings.
The various species occur in a wide range of habitats, ranging from dry, sparsely wooded country to rainforest. The vast majority are found at low levels, but some members of the genus Campylorhynchus and both members of the genus Odontorchilus are commonly found at canopy height. A few species, notably the Winter Wren and the House Wren, are often associated with humans. Most species are non-migratory, remaining in Central and South America all year round, but the few temperate species typically migrate to warmer climes in winter. Wrens build dome-shaped nests, and may be either monogamous or polygamous, depending on species.