Combustion: Combustion is a chemical process in which a substance combines with oxygen present in the air to produce new substances and release energy in the form of heat and light.
Any substance that is burned in the air to give out heat and light is called fuel.
Fuels burn in the presence of oxygen to produce carbon dioxide and water vapour as by-products and release energy in the form of heat and light.
The energy produced during the combustion or burning of fuels is used to cook food, run automobiles, produce energy in industries and for various other purposes.