how do we chemically define 'fire'?i just wanted wat its really made up of

Fire is the visible result of the chemical reaction called
combustion. For combustion to occur, the following reagents must be present: diverse
types of fuels and oxygen, but there will be no fire if heat is not present. Therefore,
the heat will bring the fuel to it's combustion temperature and the fire will go on if
the amounts of heat, fuel and oxygen are adequately.

Since
combustion happens only between gases, the solid or liquid fuel is heated till gases
will be released from it's surface.

The visible feature
that prove that the combustion is complete is the color of the flame, which has to be
blue, while, in case of incomplete combustion, the flame is
yellowish.