Combustion Combustion is the process by which something burns.
Combustion is a chemical reaction between a carbon-containing fuel and oxygen in the atmosphere.
To start and continue, the reaction requires heat. The fire triangle illustrates the three key components that keep a fire burning. A fire only keeps burning if it has enough fuel, oxygen, and heat. Fuel is any substance that can burn. For example, gasoline, paper, candle wax, and trees all burn.