Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are used as thickeners, components of some lubricants, and precursors to catalysts. Soap is created by mixing fats and oils with a base, as opposed to detergent which is created by combining chemical compounds in a mixer. Humans have used soap for millennia. Evidence exists of the production of soap-like materials in around 2800 BC in ancient Babylon.