What is combustion?

   Combustion, or burning, is a chemical reaction that gives off heat and light. All forms of combustion are oxidation reactions. In the most familiar forms of combustion the burning substance combines with oxygen, giving off energy in the form of heat and light. In less familiar forms the burning substance reacts with elements other than oxygen. For example, any substance that burns in oxygen will burn in fluorine or chlorine.
   Three conditions are necessary for combustion. First, there must be a supply of fuel. A fuel is any substance that will burn. Second, oxygen or another oxidizing agent must be available to mix with the fuel. Third, the temperature must be high enough to ignite the mixture.