The Scottish Lowlands (a' Ghalldachd, meaning roughly 'the non-Gaelic region', in Gaelic, and called Lawlands or Lallans in Scots), although not officially a geographical area of the country, in normal usage is generally meant to include those parts of Scotland not referred to as the Highlands (or Gàidhealtachd), that is, everywhere due south and east of a line (the Highland Boundary Fault) between Stonehaven and Helensburgh (on the Firth of Clyde). Confusingly, some parts of the Lowlands, such as the Southern Uplands are not physically 'low', and some sections of the Highlands, such as Islay are low-lying.
It therefore includes the traditional Scottish counties of Ayrshire, Berwickshire, Clackmannanshire, Dumfriesshire, East Lothian, Fife, Kinross-shire, Kirkcudbrightshire, Lanarkshire, Mid-Lothian, Peeblesshire, Renfrewshire, Roxburghshire, Selkirkshire, West Lothian and Wigtownshire.
Although Caithness, is sometimes classified under Highlands and Islands, it is also often considered 'Lowland' and are differentiated from the Gàidhealtachd when, for example, discussing Lowland Scots (although sections of Caithness spoke Gaelic into the 20th century). Orkney and Shetland are sometimes called 'lowland', mainly because of their current language, but have a separate identity derived from the Norse to the point of some islanders not considering themselves Scottish.
Geographically, Scotland is divided into three distinct areas: the Highlands, the Central plain (Central Belt), and the Southern Uplands. The Lowlands cover roughly the latter two. Strictly speaking, the northeast plain is also low-land, both geographically and culturally, but in some contexts may be grouped together with the Highlands.
The southernmost counties of Scotland, nearest the border with England, are also known as the Borders. They are sometimes considered separately to the rest of the Lowlands. Many descendants of the Scots-Irish, as they are known in the United States, or Ulster-Scots, originated from the lowlands and borders region before having migrated to the Ulster Plantation in the 17th century and later the American frontier, many prior to the American Revolution.