All Scotch whisky was originally made from malted barley. Commercial distilleries began introducing whisky made from wheat and rye in the late 18th century. Scotch whisky is divided into five distinct categories: single malt Scotch whisky, single grain Scotch whisky, blended malt Scotch whisky, blended grain Scotch whisky, and blended Scotch whisky.
Scotland was traditionally divided into four regions: The Highlands, The Lowlands, The Isle of Islay, and Campbeltown. Due to the large number of distilleries found there, the Speyside region is now also recognized by the Scotch Whisky Association (SWA) as a distinct region. The whisky-producing islands other than Islay are not recognised as a distinct region by the SWA, which groups them into the Highlands region.