Did you know there are two types of buttermilk?
The liquid leftover from making butter is known as traditional buttermilk. Traditional buttermilk is very low in fat (since most of the fat went to making the butter). It can be consumed as a beverage (try it with fresh ground pepper) or added to recipes in place of water for a nutritional boost.
Cultured buttermilk is generally what is called for in recipes. It is also the type of buttermilk you find in the store or you can make your own using a Cultured Buttermilk Starter. Cultured buttermilk is very similar to yogurt in the sense that it is cultured using live beneficial bacteria. Cultured buttermilk can be consumed as a thick and creamy beverage or used in cooking (pancakes anyone?).