Butter is a semi-solid dairy product made from churning milk or cream, which separates the butterfat from the buttermilk. This process inverts the structure of the dairy product from an oil-in-water emulsion to a water-in-oil emulsion, resulting in the creamy spread we know. Most commercially sold butter is made from pasteurized cow's milk, though it can also be made from the milk of other mammals like goats, sheep, and yaks.
Chemical composition
Standard commercial butter is legally required to contain a minimum of 80% milkfat in the U.S. and 82% in Europe. The typical breakdown is:

:p