Whiskey is a type of liquor made from fermented grain mash. The primary ingredients that make up whiskey are cereal grains, typically barley, wheat, corn, and rye. The exact mix of grains that each specific brand and distiller of whiskey depends on that distillers special recipe, as well as the requirements of more specific categories of whiskey. The recipe of the mash, known as the mash bill, is what distinguishes different types of whiskey. The mash is fermented with yeast, which converts the sugars in the grains into alcohol. The resulting liquid is then distilled to increase the alcohol content and create a spirit. The distilled liquid is then aged in wooden casks, which are typically made of charred white oak. The type of cask used can also affect the flavor of the whiskey. The aging process allows the flavor to mature, evolve, and mellow into something more complex. The final product must have an alcohol by volume (ABV) of at least 40% .

In summary, whiskey is made of:

• Cereal grains, typically barley, wheat, corn, and rye
• Yeast
• Water
• Wooden casks, typically made of charred white oak

The exact mix of grains and type of cask used can vary depending on the specific brand and type of whiskey.