The ring ouzel is a mainly European member of the thrush family Turdidae. It is a medium-sized thrush, 23–24 centimetres (9.1–9.4 in) in length and weighing 90–138 grams (3.2–4.9 oz). The male is predominantly black with a conspicuous white crescent across its breast. Females are browner and duller than males, and young birds may lack the pale chest markings altogether. In all but the northernmost part of its range, this is a high-altitude species, with three races breeding in mountains from Ireland east to Iran. It breeds in open mountain areas with some trees or shrubs, the latter often including heather, conifers, beech, hairy alpenrose or juniper. It is a migratory bird, leaving the breeding areas to winter in southern Europe, North Africa and Turkey, typically in mountains with juniper bushes. The typical clutch is 3–6 brown-flecked pale blue or greenish-blue eggs. They are incubated almost entirely by the female, with hatching normally occurring after 13 days. The altricial, downy chicks fledge in another 14 days and are dependent on their parents for about 12 days after fledging.

The thrushes are a passerine bird family, Turdidae, with a worldwide distribution. The family was once much larger before biologists reclassified the former subfamily Saxicolinae, which includes the chats and European robins, as Old World flycatchers. Thrushes are small to medium-sized ground living birds that feed on insects, other invertebrates and fruit. Some unrelated species around the world have been named after thrushes due to their similarity to birds in this family.