Single malt, pot-still whisky. taken straight from the cask with only one course filtration, is Scotch whisky in its most authentic form. Malt whiskies vary greatly in smell and taste. Each is complex in character and highly individual, its uniqueness deriving from a combination of qualities of water, barley, peat, and the skills of brewer and distiller. As important as all of these is the nature of the cask in which the whisky is matured.