Whisky is not made or produced, it is carefully crafted to perfection. The principles of distillation have changed little over the last two centuries, and still follow the five step process.
Barley contains starch, which converted to soluble sugars to make alcohol. For this, the barley undergoes germination, which is called 'malting'. After this, the barley is soaked for two to three days in warm water, and then spread on the floor. When the barley starts to shoot, the germination is stopped by drying it in a kiln. Traditionally, peat is used to power the kiln. The type of peat used along with the length of drying in the peat smoke influences the flavour of the final spirit. The barley is now called 'malt', and this is ground down in a mill, with any husks removed.
The grounded malt, which is called 'grist', is added to warm water to begin the extraction of the soluble sugars. The character of water also influences the final spirit, as it may contain minerals from passing over granite, peat or other rocks. The liquid combination of malt and water is called the 'mash'. It is then put into a large vessel called a mash tun and stirred for several hours. When the sugars in the malt dissolve and drawn off through the bottom of the mash tun, the resulting liquid is called 'wort'. Any residue, such as husks, is called 'draff'.
The wort is cooled and passed into large tanks called 'washbacks'. These are traditionally made of wood. The yeast is added and the fermentation begins. The yeast turns the sugars into alcohol. As with the barley and water, the distiller carefully selects the strain of yeast as it also has a significant effect on the final flavour of the spirit. The fermentation normally takes around 48 hours to run its natural course, although some distilleries will let it go for longer so as to enrich the characteristics that they require. The liquid at this stage is called 'wash' and is low in alcohol strength (between 5-10% ABV), like beer or ale.
In Scotland, the wash is traditionally distilled twice. In Ireland, it is distilled three times, although there are exceptions in both countries. After distillation, the wash enters the larger wash still and is heated. The liquid vaporises and rises up the still until it reaches the neck, where it condenses. This liquid is called 'low wines' and is unusable. These are then passed to the second smaller still called the spirit still. Alcohols from the beginning of the distillation are very high in spirit level and very pungent. Alcohols from the end are weak but pungent. It is only the alcohol from the middle or 'heart' of the distillation that is used, and this is skillfully removed by a stillman and collected through the spirit safe.
The spirit is put into oak casks and stored. The spirit must mature in casks for a minimum of three years before it is legally allowed to be called whisky in Scotland. During maturation, the flavours of the spirit combine with natural compounds in the wood cask that gives the whisky its own characteristic flavour and aroma. Wood is porous, so over time it breathes in air from the surrounding environment in which it is stored. The location of distillery storage facilities, like next to the sea, on an island or in the middle of the Highlands, and the air quality, temperature, and humidity influence the end product. During each year of maturation, about 2% of the spirit is lost through natural evaporation. This is called the "angel's share" and explains why older whiskies are less readily available and more expensive to buy.