Whiskey is a distilled spirit made from fermented grain. It is aged in wooden barrels, usually made from white oak that have been charred. Some whiskies are distilled several times.
Malt whiskey is made using only malted barley, without other grains. In contrast, grain whiskey is made by mixing malted barley with other grains.
Different forms of whiskey use different grains. The legal systems of various countries define the types.
Bourbon whiskey is made from corn. It was invented in Bourbon County, Kentucky and is a distinctly American product.
Scotch whiskey is made in Scotland from malted barley plus other grains. The smoky flavor comes from drying the malted barley over a peat fire.
Rye, wheat, and corn whiskies are made from the respective grain