A magneto is an electrical generator that uses permanent magnets to produce pulses of high voltage alternating current. At one time the magneto was used in the ignition system of most gasoline-powered internal combustion engines to provide power to the spark plugs. The magneto is now confined mainly to lawnmowers, chainsaws, and internal-combustion aviation engines. People discussing magnetos and coils used in early internal-combustion engines generally used the term "tension" instead of the more modern term "voltage."