What is the function of a spark plug in a gasoline engine?

The function of a spark plug in a gasoline engine is to ignite the air-fuel mixture within the engine's combustion chamber. When the piston moves down, the air-fuel mixture is drawn into the chamber and compressed. Once the piston reaches the top of its stroke, the spark plug produces a high-voltage spark that ignites this mixture, causing a controlled explosion. This explosion pushes the piston down again, creating the power needed for the engine to operate.

While other components like the fuel injection system control the delivery of fuel, and there are filters that remove impurities from the fuel before it reaches the engine, the specific role of the spark plug is crucial to initiating the combustion process. Additionally, while electricity is generated within the ignition system, the spark plug itself does not generate electricity; it uses the high-voltage charge delivered by the ignition coil to create the spark needed for ignition.