Major parts of the engine are cylinders, it is the car's power source.
Cylinder including cylinder, the air intake, oil holes, vent, pistons and spark plugs (petrol engine).
Cylinders through the air intake and gas and air the oil hole, mix in the cylinder, when after the mixture is ignited the spark plug, violently explosive combustion of the mixture, and push the piston downward, and generate power. Meanwhile, pushing aside the explosive gas huge pressure check valve vent and exhaust. Then, remaining in the cylinder gas becomes cold, low pressure, atmospheric pressure and the outside of the cylinder piston moves, in preparation for the next explosion. This is the simple truth. Is also used as a term for IT, packaged libraries, others call, such as search engines, graphics engine, a physics engine, and so on.