ignition

Ignition systems are used by heat engines to initiate combustion by igniting the fuel-air mixture. In a spark ignition versions of the internal combustion engine (such as petrol engines), the ignition system creates a spark to ignite the fuel-air mixture just before each combustion stroke. Gas turbine engines and rocket engines normally use an ignition system only during start-up.
Diesel engines use compression ignition to ignite the fuel-air mixture using the heat of compression and therefore do not use an ignition system. They usually have glowplugs that preheat the combustion chamber to aid starting in cold weather.
Early cars used ignition magneto and trembler coil systems, which were superseded by Distributor-based systems (first used in 1912). Electronic ignition systems (first used in 1968) became common towards the end of the 20th century, with coil-on-plug versions of these systems becoming widespread since the 1990s.

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