A machair is a fertile low-lying grassy plain found on part of the northwest coastlines of Ireland and Scotland, in particular the Outer Hebrides. The best examples are found on North and South Uist, Harris and Lewis.

The Outer Hebrides or Western Isles, sometimes known as the Long Isle or Long Island, is an island chain off the west coast of mainland Scotland. The islands are geographically coextensive with Comhairle nan Eilean Siar, one of the 32 unitary council areas of Scotland. They form part of the archipelago of the Hebrides, separated from the Scottish mainland and from the Inner Hebrides by the waters of the Minch, the Little Minch, and the Sea of the Hebrides.