Explain combustion and combustible along with examples.

The chemical process in which a substance reacts with oxygen to give off heat is called combustion. In combustion the release of heat can result in the production of light in the form of either glowing or a flame. The substance which undergoes combustion is called combustible or fuel. Fuel may be solid, liquid or gas. Example: Burning of a coal shows the process of combustion and coal here is combustible or fuel.