An ingredient is a substance that forms part of a mixture (in a general sense). For example, in cooking, recipes specify which ingredients are used to prepare a specific dish. Many commercial products contain a secret ingredient that is purported to make them better than competing products. In the pharmaceutical industry, an active ingredient is that part of a formulation that yields the effect expected by the customer. National laws usually require prepared food products to display a list of ingredients, and specifically require that certain additives be listed.