The process of combustion is a high speed, high temperature chemical reaction. It is the rapid union of an element or a compound with oxygen that results in the production of heat essentially, it is a controlled explosion.
Combustion occurs when the elements in a fuel combine with oxygen to produce heat.
All fuels, whether they are solid, liquid or in gaseous form, consist primarily of compounds of carbon and hydrogen called hydrocarbons. Sulfur is also present in these fuels. When the hydrogen and oxygen combine, intense heat and water vapor is formed. When carbon and oxygen combine, intense heat and the compounds of carbon monoxide or carbon dioxide are formed. When sulfur and oxygen combine, sulfur dioxide and heat are formed.