The primary ingredient used to make whiskey is grain. Various types of grains can be utilized, including barley, corn, rye, and wheat, depending on the specific type of whiskey being produced. The grains are mashed, fermented, distilled, and then aged in wooden barrels, often oak, which contributes to the flavor and character of the final product. The type of grain used significantly influences the taste profile of the whiskey; for example, bourbon primarily uses corn, while rye whiskey is known for its spicy flavor derived from rye grain. This process leads to the diverse varieties of whiskey enjoyed worldwide.