Food additives are substances added to food to preserve flavor or enhance its taste and appearance. To regulate these additives, and inform consumers, each additive is assigned a unique number, termed as "E numbers", which is used in Europe for all approved additives. There are natural and synthetic food additives that are used for a variety of purposes categorized in acidity regulators, anticaking agents, antifoaming agents, antioxidants, bulking agents, food coloring, color retention agents, emulsifiers, flavor enhancers, humectants, preservatives, stabilizers, sweeteners, thickeners, etc.