Whiskey is a type of distilled alcohol made from fermented grain mash. Various are used for different varieties, including barley, corn, rye and wheat. Whiskey is typically aged in wooden casks, made of charred white oak. Whiskey is a strictly regulated spirit worldwide with many classes and types. The typical unifying with 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 whiskey is only the time between distillation and bottling. This reflects how much the cask has interacted with the whiskey, changing its chemical makeup and taste. After a decade or two, additional aging in a barrel does not necessarily improve a whiskey.