Bourbon is made mostly from a mixture of grain known as a mash bill, which must have no less than 51% corn. The remaining grains often include wheat, barley, and other types of grains, each adding unique flavor notes. This mash is fermented, distilled, and aged in charred barrels made from oak wood. The high corn content gives bourbon its natural sweetness, while the aging process adds depth, smoothness, and rich character that distinguishes it from other whiskeys.