E numbers are codes for substances that are permitted to be used as food additives for use within the European Union. Commonly found on food labels, their safety assessment and approval are the responsibility of the European Food Safety Authority (EFSA).

Having a single unified list for food additives was first agreed upon in 1962 with food colouring. In 1964, the directives for preservatives were added, 1970 for antioxidants and 1974 for the emulsifiers, stabilisers, thickeners and gelling agents.

E100–E199 (colours)
E200–E299 (preservatives)
E300–E399 (antioxidants, acidity regulators)
E400–E499 (thickeners, stabilisers, emulsifiers)
E500–E599 (acidity regulators, anti-caking agents)
E600–E699 (flavour enhancer)
E700–E799 (antibiotics)
E900–E999 (glazing agents and sweeteners)
E1000–E1599 (additional chemicals)

Source: https://webgate.ec.europa.eu/foods_system/main/?event=display