Ranch dressing is a savory, creamy American salad dressing usually made from buttermilk, salt, garlic, onion, mustard, herbs, and spices mixed into a sauce based on mayonnaise or another oil emulsion. Sour cream and yogurt are sometimes used in addition to, or as a substitute for, buttermilk and mayonnaise.

Buttermilk is a fermented dairy drink. Traditionally, it was the liquid left behind after churning butter out of cultured cream. As most modern butter in Western countries is not made with cultured cream but uncultured sweet cream, most modern buttermilk in Western countries is cultured separately. It is common in warm climates where unrefrigerated milk sours quickly.