Cream is a dairy product composed of the higher-fat layer skimmed from the top of milk before homogenization. The butterfat, which is less dense, rises to the top and is skimmed off, resulting in gravity cream. The industrial production of cream instead uses centrifugal separators to make separator cream. Cream is often sold in grades defined by their butterfat content. It contains high levels of saturated fat, in ascending proportion from light cream to heavy cream.