Caramel colouring is caramel used as a food colouring; it is made by controlled heating of sugar, generally in the presence of acids or alkalis and possibly other compounds, a process called caramelization. Unlike caramel candy, it tends towards maximum oxidation of the sugar to produce a caramel concentrate that is unpalatable in its raw liquid form. Its colour ranges from dark brown to black.

There are four types of caramel, differing in their method of manufacture and application, each with its own E number:

• Plain caramel, caustic caramel, or spirit caramel (Class I): E150a, contains sugar and sometimes acids, alkalis, and salts other than ammonium and sulphite compounds.
• Caustic sulphite caramel (Class II): E150b, may contain sulphite compounds.
• Ammonia caramel, baker's caramel, confectioner's caramel, or beer caramel (Class III): E150c, may contain ammonium compounds; used in beer, synthetic soy sauce, and confectionery.
• Sulphite ammonia caramel, acid-proof caramel, or soft-drink caramel (Class IV): E150d, may also contain both ammonium and sulphite compounds; used in acid environments such as soft drinks.