Buttermilk is a type of milk. It is used for a variety of purposes. Certain types of biscuits are made with buttermilk. This type of biscuit is called a buttermilk biscuit. Wendy liked to make buttermilk biscuits, and she often realized that she used to mix the buttermilk too slowly and it made for bad biscuits, so she started mixing it quicker, and the biscuits turned out great.