Ranch dressing is a savory, creamy American salad dressing usually made from buttermilk, salt, garlic, onion, mustard, herbs (commonly chives, parsley, and dill), and spices (commonly pepper, paprika, and ground mustard seed) 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. Ranch has been the best-selling salad dressing in the United States since 1992 when it overtook Italian. It is also popular in the United States and Canada as a dip and as a flavoring for potato chips and other foods. In 2017, 40% of Americans named ranch as their favorite dressing, according to a study by the Association for Dressings and Sauces.

Source: Wikipedia