Whiskey, also spelled whisky, is a distilled alcoholic beverage made from fermented grain mash. The major whiskey producing regions are Scotland, Ireland, Kentucky, and Tennessee. The whiskey making process involves malting barley or other grains, fermenting the mash into a "wash," distilling the wash, and aging the distilled spirit in wooden casks. The type of cask and number of years of aging determines the characteristics of the whiskey. Glasses like the old fashioned glass, rocks glass, and snifter are used to best enjoy the different styles of whiskey.