Cow's milk is the milk produced by domestic cows, used both on its own and as the base for most dairy products. Cattle were domesticated roughly 10,000 years ago in the Fertile Crescent, and cow's milk has been a food staple since early agricultural societies.
It's composed mostly of water, fat, protein, and lactose, with a composition that varies by breed, diet, and stage of lactation, producing a mildly sweet, creamy liquid. Cow's milk is the base for cheese, yogurt, butter, and cream, and is used directly in baked goods, sauces, soups, custards, puddings, and ice cream, where it adds richness, body, and moisture.
Common variations include whole, low-fat, and non-fat milk, which differ mainly in fat content and how they behave in cooking - lower-fat milk curdles more easily and adds less richness. Raw and organic milk are also sold, though raw milk carries food-safety risks that pasteurization is designed to eliminate.