The word ‘machair’ is Gaelic, meaning an extensive, low-lying fertile plain. Gaelic is not native to Orkney and Shetland but elsewhere ‘machair’ features in placenames, such as Machrihanish in Kintyre, Machair Bay in Islay, Magheramore and Maghera Strand in Ireland, and in places in the Outer Hebrides. ‘Machair’ has now become a recognised scientific term for a specific coastal feature, defined by some as a type of dune pasture (often calcareous) that is subject to local cultivation, and has developed in wet and windy conditions. This rather restricts the term to the grassy plain alone. Other authorities prefer to consider the whole system, from the beach to where the sand encroaches on to peat further inland; this is the definition used here. Machair is one of the rarest habitats in Europe, found only in the north and west of Britain and Ireland. Almost half of the Scottish machair occurs in the Outer Hebrides, with the best and most extensive in the Uists and Barra, and also Tiree. Machair sand has a high shell content, sometimes 80 or 90%. This helps distinguish it from the ‘links’ of eastern coasts, which are formed from more mineral-based sand.