"A rapid oxidation process, which is a chemical reaction resulting in the evolution of light and heat in varying intensities" - NFPA 921
A fire is an exothermic chemical reaction that emits heat and light - Dictionary
Fire happens due to chemical reactions between the source of heat, oxygen and combustible material. It can easily be define with the simple graphical representation of "fire reaction" as below;
Several source of heat can be noticed in our everyday life. Among the source of heat are electric, static electric, sparks, mechanical heat and lightning. Meanwhile the combustible material is the material that usually we have in our place. Materials such as combustible liquids (e.g. petrol, diesel), combustible solids (e.g. furniture, paper) and also combustible gases (e.g. methane, butane).
Fire usually happens when there is a chain reaction between these elements. It undergo the process of pyrolysis which produce heat, light and smoke.
