Buttermilk is a fermented dairy product. Most modern buttermilk is cultured, meaning that beneficial bacteria have been added to it. It’s different from traditional buttermilk, which is rarely found in Western countries today. This article refers to cultured buttermilk simply as buttermilk. This dairy product is most often used in baking. For example, it’s a common ingredient in biscuits, muffins, quick breads, and pancakes. It can also be used in batters for fried foods or as a creamy base in soups, potato salad, or salad dressings.