Fire is a form of combustion. Most typically, the word fire refers to the combination of the brilliant glow and large amount of heat released during a rapid, self-sustaining exothermic oxidation process of combustible gases ejected from a fuel.
The flames are a body of gas that releases heat and light. Fires start when a fuel is subjected to heat or another energy source, e.g. a match or lighter, and are sustained by the further release of heat energy until all the combustible fuel is consumed.