An internal combustion engine is any engine in which the expansion of the high temperature and high-pressure gases produced by combustion of a fuel with an oxidizer (usually air) exerts a direct force on some components of the engine, usually pistons, turbine blades, a rotor, or a nozzle. This force moves the components over a short distance, which causes a mechanically linked shaft to rotate.
Internal combustion engines provide outstanding performance and durability, powering more than 1.4 billion road transportation vehicles worldwide as well as boats and railroad locomotives. They are also used in numerous other applications, including industrial equipment, agricultural machinery, landscaping tools and recreational equipment.
In addition to gasoline and diesel fuel, internal combustion engines can also utilize renewable or alternative fuels, including biodiesel, ethanol, natural gas and propane, and they can be used in plug-in hybrid electric systems to extend the range of hybrid electric vehicles.