Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Fuel is any material that stores energy that can be extracted to perform mechanical work in a controlled manner. Most fuels that are used by humans undergo combustion which is a reaction in which the substance releases energy after it ignites and reacts with the oxygen in the air. Fuel is a term which is often used to represent the liquid petroleum and natural gas that are used in vehicles and machinery as they are the most utilised type of fuels. However, petroleums, natural gas, and oil form part of the category of fossil fuels, Other types of fuels are biofuel, chemical fuel and nuclear fuel... Learn more about fuel, petroleum prices, and fuel management with the help of this book.