The element necessary for fire to burn is oxygen. Fire is a chemical reaction that occurs when a combustible material reacts rapidly with an oxidizing agent, typically oxygen in the air. This reaction produces heat, light, and combustion products like carbon dioxide and water vapor. For a fire to ignite and sustain, there must be a sufficient supply of oxygen. This is why fires can be extinguished by cutting off their oxygen supply, either by smothering them or using fire extinguishers. The triangle of fire highlights the need for fuel, heat, and oxygen for combustion to occur.