The document discusses the operation of ignition systems. It describes how the ignition system uses a battery, ignition switch, ignition coil, distributor, and spark plugs. The ignition coil transforms low battery voltage into high voltage to create an electric spark at the spark plugs. This spark ignites the air-fuel mixture in the engine cylinders. The distributor times the spark to each cylinder based on the engine's speed and load. Electronic ignition systems have replaced older contact point systems and improve timing control.