The Outer Hebrides, or Western Isles, comprise an island chain off the west coast and is part of the Hebrides, separated from the Scottish mainland and from the Inner Hebrides by the stormy waters of the Minch, the Little Minch and the Sea of the Hebrides. Scottish Gaelic was formerly the dominant language, and remains widely spoken even though in some areas English is now the main language. The main islands form an archipelago. With their smaller surrounding islands these are sometimes known poetically as the Long Isle. The major islands include Lewis and Harris, North Uist, Benbecula, South Uist, and Barra. Much of the western coastline of the islands is machair, a fertile low-lying dune pastureland. Much of the archipelago is protected habitat, and this includes both the islands and the surrounding waters. There are numerous rare species, including the golden eagle, basking shark, whale, dolphin, otter and corncrake.

There are numerous uninhabited islands including the Barra Isles, Flannan Isles, Monach Islands, the Shiant Isles and the islands of Loch Ròg. In common with the other main island chains of Scotland many of the more remote islands were abandoned during the 19th and 20th centuries, in some cases after continuous habitation since the prehistoric period. This process involved a transition from these places being perceived as relatively self-sufficient agricultural economies to a view becoming held by both island residents and outsiders alike that the more remote islands lacked the essential services of a modern industrial economy. The modern commercial activities centre on tourism, crofting, fishing, and weaving including the manufacture of Harris tweed.