Ayrshire (Scottish Gaelic: Siorrachd Inbhir Àir, pronounced [ˈʃirˠəxk iɲiˈɾʲaːɾʲ]) is an historic county and registration county, in south-west Scotland, located on the shores of the Firth of Clyde. The lieutenancy area of Ayrshire and Arran covers the entirety of the historic county as well as the island of Arran, formerly part of the historic county of Buteshire. Its principal towns include Ayr, Kilmarnock and Irvine and it borders the counties of Renfrewshire and Lanarkshire to the north-east, Dumfriesshire to the south-east, and Kirkcudbrightshire and Wigtownshire to the south. Like many other counties of Scotland, it currently has no administrative function, instead being sub-divided into the council areas of East Ayrshire, North Ayrshire and South Ayrshire. It has a population of approximately 366,800.
The electoral and valuation area named Ayrshire covers the three council areas of East Ayrshire, North Ayrshire and South Ayrshire, therefore covering the whole historic county of Ayrshire but also including the Isle of Arran, Great Cumbrae and Little Cumbrae from the historic county of Buteshire. The three council areas together also form the Ayrshire and Arran lieutenancy area.