Bourbon Whisky must contain a minimum of 51% corn, be produced in the United States, be distilled at less than 80% ABV (160 proof) and be aged in new charred oak barrels; 'straight' bourbon must be aged for a minimum of two years, although in practice virtually all straight whiskies are aged at least four years. Any bourbon, or any other domestic or imported whiskey, for that matter, that has been aged less than four years must contain an age statement on the label. Small Batch Bourbons are bourbons that bottled from a small group of specially selected barrels that are blended together. It should be noted though that each distiller has their own interpretation of what constitutes a "small batch." Single Barrel Bourbon is bourbon from one specifically chosen cask.

A Cask-Finished Straight Bourbon Whiskey will undergo additional maturation in one or more barrels, the previous contents of which contribute to the aromas and flavors of the final product. Examples include but are not limited to used Rum, Cognac, Port, Sherry, Madeira, Stout, and maple barrels.