20 JUL 2017 · A spark plug is an electrical device that ignites compressed fuels such as aerosol, gasoline in internal combustion engines to initiate combustions.
Simply put, a spark plug is a device in the engine that aids it to ignite in. Spark plugs have a wide application in combustion engines such as those found in cars, boats, lawn mowers, generators amongst lots of combustion engines.
Source: http://coolcaraccessories.net/best-spark-plug-reviews/