Ignition, system used to start an engine. In an internal combustion engine the ignition system sets fire to a mixture of fuel and air to generate power. Most automobiles use spark ignition systems, in which spark plugs create electric sparks to set fire to fuel. When a spark ignition system is turned on, an electric current flows from a battery to the ignition coil, where it is increased in voltage and then sent to a distributor. In the distributor, a rotor directs the current to the automobile's set of spark plugs. At this point, the spark plugs produce the electric sparks that ignite the fuel and air mixture to start the engine.
See also: Engine.