Regardless of what spelling you use (whisky vs. whiskey), generally, whisky is a spirit made from fermented grain mash. The specific grain used, such as rye, wheat, barley or corn, depends on the final variety. Each type completely differs from the next because every country's regulations shape the production process. Scotch must be aged for a minimum of three years in oak barrels, while U.S. bourbon is required to contain at least 51 percent corn and is aged in charred, new oak barrels. With all the rules, varieties and classifications, navigating the vast, complex world of whisky (and whiskey) can be difficult. Food & Wine's guide helps you discover more about what you're drinking with easy-to-understand information and delicious recipes.