Even though its name might suggest otherwise, buttermilk is a low-fat dairy product made from cow's milk. Originally, it was made from the liquid left after milk was churned into butter. Now, it is far more likely to be processed from nonfat or low-fat milk and treated with a special strain of bacteria to thicken it and add its characteristic tang.

In addition to its use as a beverage, buttermilk is used for making salad dressings, chilled soups and as an ingredient in pancake, cake and quick bread recipes. Buttermilk can be found primarily in quart and half gallon containers, although pints are increasingly available. Shake the carton before using. Buttermilk also is sold in powdered form, a welcome convenience for those who use buttermilk only for baking purposes. It is shelf-stable and can be reconstituted with water.