Johnnie Walker Black Label 12 Years iconic square bottle makes it one of the world's most recognisable Scotch whiskies - and it's also one of whisky critic Jim Murray's favourite blends: 'If there is a silkier delivery on the market today, I have not seen it: this is sublime stuff...one of the world's most masterful whiskies back in all its complex glory.Whisky or whiskey is a type of distilled alcoholic beverage made from fermented grain mash. Various grains (which may be malted) are used for different varieties, including barley, corn (maize), rye, and wheat. Whisky is typically aged in wooden casks, generally made of charred white oak.Whisky is a strictly regulated spirit worldwide with many classes and types. The typical unifying characteristics of the different classes and types are the fermentation of grains, distillation, and aging in wooden barrels.Whiskies do not mature in the bottle, only in the cask, so the "age" of a whisky is only the time between distillation and bottling. This reflects how much the cask has interacted with the whisky, changing its chemical makeup and taste. Whiskies that have been bottled for many years may have a rarity value, but are not "older" and not necessarily "better" than a more recent whisky that matured in wood for a similar time. After a decade or two, additional aging in a barrel does not necessarily improve a whisky.While aging in wooden casks, especially American oak and French oak casks, whisky undergoes six processes that contribute to its final flavor: extraction, evaporation, oxidation, concentration, filtration, and colouration. Extraction in particular results in whisky acquiring a number of compounds, including aldehydes and acids such as vanillin, vanillic acid, and syringaldehyde.