Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest halogen and is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour.

A wide variety of organobromine compounds are used in industry. Some are prepared from bromine and others are prepared from hydrogen bromide, which is obtained by burning hydrogen in bromine.

Brominated flame retardants represent a commodity of growing importance, and make up the largest commercial use of bromine.