A combustion reaction is a chemical process where a substance, usually a fuel like gasoline or wood, reacts with oxygen to produce heat and light. This reaction typically results in the formation of carbon dioxide and water as byproducts. For example, when you burn wood in a fireplace, the wood combines with oxygen in the air, releasing energy in the form of heat and light. There are two main types of combustion: complete and incomplete. In complete combustion, there is enough oxygen for the fuel to burn fully, producing mainly carbon dioxide and water. In incomplete combustion, insufficient oxygen leads to the production of carbon monoxide and soot, which can be harmful to health and the environment.