Fire is a form of combustion. Linguistically, the word fire refers to the combination of the brilliant glow and large amount of heat released during a rapid, self-sustaining burning of combustible fuel. Technically, fire is not a state of matter; it is an exothermic oxidation process by which heat and light energy are given out. Fire starts when a fuel with adequate oxygen supply is subjected to enough heat, and it is sustained by the further release of heat energy in the process, as well as a continuous supply of oxygen and combustible fuel. A match or lighter is usually used to start a fire (which can then propagate to other combustibles) because matches and lighters are designed with materials of low burning point. Fire is extinguished when one or more of heat, oxygen, and fuel is removed.
Flames can conduct electricity, as a small portion of any fire is ionized. This has been demonstrated in the laboratory and also in large wildfires that occur in the vicinity of power lines.
