Vintage bourbon whiskey refers to bourbon that has been aged for an extended period, typically well beyond the minimum aging requirements set by law. Bourbon is a type of American whiskey that is primarily made from corn and aged in charred oak barrels.

To be called bourbon, the whiskey must meet certain legal requirements in the United States. It must be made from a grain mixture that is at least 51% corn, distilled to no more than 160 proof (80% alcohol by volume), entered into the barrel for aging at no more than 125 proof (62.5% alcohol by volume), and be aged in new, charred oak barrels. Additionally, bourbon must be aged for a minimum of two years to be labeled as "straight bourbon."

Vintage bourbon whiskey is typically aged for a longer period than the minimum requirement. The aging process in oak barrels imparts flavors and aromas to the whiskey, giving it complexity and mellowing harsh flavors. Over time, the bourbon takes on characteristics from the wood, such as vanilla, caramel, and oak notes. The longer the bourbon ages, the more time it has to develop these flavors and become smoother.

Vintage bourbons are highly sought after by whiskey enthusiasts and collectors due to their rarity and the unique flavors that develop over time. They often command higher prices in the market, particularly if they are from a well-known distillery or have other desirable qualities such as limited production or special releases.