An additive is defined as: any natural or synthetic material, other than the basic raw ingredients, used in the production of a food item to enhance the final product or any substance that may affect the characteristics of any food, including those used in the production, processing, treatment, packaging, transportation or storage of food.

Food additives are often referred to as E-numbers (see the E-number section of the site), as in the EU countries additives are numbered with a prefix E. The E thus refers to an approved additive.

Additives are not used to mask problems (such as spoiling) in the food, but are often used to prevent spoilage or other loss of quality.

There are many categories of food additives, such as :

- acididity regulators and buffers

- anti-caking agents

- anti-oxidants

- bread enhancers

- emulsifiers

- food colours

- preservatives

- stabilisers

- thickening agents

All are tested for toxicity and safety. However, side effects can never completely be excluded. See the individual E-numbers for toxicity and safety data.