Few cocktails are as timeless as the Old Fashioned. With just whiskey, sugar, bitters, and ice, it’s a simple drink—but the choice of bitters can dramatically change its character. If you’re wondering which bitters to use in an Old Fashioned, the answer depends on the flavor profile you want to create.

If you've ever savored an expertly crafted cocktail, you may have come across the term "bitters." But what exactly are cocktail bitters?