Single malt whisky is a whisky which is distilled and produced at just one particular distillery. Single malts are made entirely from one type of malted grain, traditionally barley, which is cultivated in the region of the distillery, (although there are also single malt rye whiskies). Most single malt whiskies are distilled using a pot still.
Single malts are globally associated with Scotland, though they are produced elsewhere, notably in Ireland and Japan. All single malt goes through a similar batch production process, as outlined below. At bottling time various batches are mixed together or vatted to achieve consistent flavours from one bottling run to the next.
Some variation does occur. Water is first added to the barley to promote germination, it is mixed with ground barley grist to create a mash and it is used to dilute most whisky before maturation and once again before bottling. Most distilleries use different water sources in the various steps, and this becomes a crucial part of the character of the end product.