Whiskey (or whisky) is the overarching term for a distilled alcohol made with a grain mash that generally includes rye, corn, barley, or wheat. The three main categories of whiskey are Scotch, Bourbon, and Rye. To bear the name 'Scotch,' the spirit has to be made in Scotland. Generally, Scotch is made with malted barley and must be aged for at least three years in oak barrels. Bourbon must be made with at least 51% corn and manufactured in the United States; however, there's no minimum aging time. Finally, rye whiskey is either American and contains at least 51% rye or Canadian whiskey, which (confusingly) may or may not contain rye.