Ranch dressing is a type of salad dressing made of some combination of buttermilk, salt, garlic, onion, herbs (commonly chives, parsley, and dill), and spices (commonly black pepper, paprika, and ground mustard seed), mixed into a sauce based on mayonnaise or another oil emulsion. Sour cream and yogurt are sometimes used as a substitute by some home cooks or to create a lower-fat version. Ranch dressing has been the best-selling salad dressing in the United States since 1992, when it overtook Italian dressing. It is also popular as a dip.