Gas and oil are two of the most commonly used FUELS in the world. Gasoline, or petrol, is a petroleum-derived liquid fuel that is used in internal combustion engines, while oil is a combustible hydrocarbon liquid derived from petroleum. Gas and oil are both used to power vehicles, machinery, and other equipment, as well as to generate electricity. The term 'gas and oil' can also refer to the industry that produces and distributes these FUELS.