Bourbon is a type of American whiskey that has specific legal requirements defining its production, ingredients, and aging process. The distinctive characteristics of bourbon contribute to its popularity and unique flavor profile. Here are key features of bourbon:

1. **Main Ingredients:** Bourbon must be made from a grain mixture that is at least 51% corn. The remaining grains typically include malted barley, rye, and/or wheat. Corn contributes to the sweetness and richness of the final product.

2. **Distillation:** Bourbon must be distilled to no more than 160 proof (80% alcohol by volume) and entered into the barrel for aging at no more than 125 proof (62.5% alcohol by volume). Distillation must occur in the United States.

3. **Aging:** Bourbon must be aged in new charred oak barrels. There is no minimum aging requirement to be called "straight bourbon," but if the age is stated on the label, it must be the age of the youngest whiskey in the bottle.

4. **No Additives:** Bourbon cannot contain any additives, flavorings, or colorings. The flavor and color must come from the grains, the barrel, and the aging process.

5. **Proofing:** If bourbon is diluted with water, it must be done to not less than 80 proof (40% alcohol by volume) before bottling.

6. **Barrel Char and Size:** The inside of the new oak barrels used for aging bourbon must be charred. The size of the barrel is not specified, but it is typically 53 gallons.

7. **Geographical Origin:** While bourbon can be produced anywhere in the United States, it is often associated with Kentucky, and many well-known bourbon brands come from this region.

8. **Flavor Profile:** Bourbon is known for its rich and full-bodied flavor profile, with notes of caramel, vanilla, oak, and sometimes hints of spice and fruit. The charred oak barrels contribute to the deep amber color of the spirit.

9. **Straight Bourbon vs. Blended Bourbon:** "Straight bourbon" refers to bourbon that is aged for a minimum of four years and meets specific criteria, while "blended bourbon" contains a mixture of straight bourbon and other spirits.

10. **Popular Cocktails:** Bourbon is commonly used in classic cocktails, including the Old Fashioned, Manhattan, and Whiskey Sour. It is also enjoyed neat or on the rocks.

Bourbon has become an iconic American spirit, and its production is regulated by the U.S. Federal Standards of Identity for Distilled Spirits to ensure consistency and quality. The combination of specific grains, distillation methods, and aging in new charred oak barrels gives bourbon its distinct and cherished characteristics.