The importance of a spark plug is often overlooked because they are so reliable nowadays. That hasn't always been the case, though.
Way back in 1859, a Belgian engineer named Joseph Étienne Lenoir developed the first internal combustion engine. This invention used a mixture of air and coal gas, but for it to work, it required a spark to ignite the system.
According to the guys at New Mind, "Lenoir’s ignition system created sparks by using high voltage electricity to jump an air gap. This was accomplished by sending mechanically generated low voltage pulses through a type of electrical transformer known as a Ruhmkorff coil. The coil would transform the low voltage pulses into a lower current, high voltage pulses, suitable for spark generation."
Over the next 160-years, this "jumping spark" system would need to evolve multiple times to keep up with the ever-changing development of the engine. The spark plug would need to become more compact and reliable as engine performance improved.
Today, the simple spark plug is made up of a variety of materials that extract optimum performance from the fuel they ignite. But, as technology evolves once again, the spark plug is in danger of going extinct.
Although internal combustion engines will be around for a very long time, new propulsion units by motor manufacturers are going electric, and the spark plug will be relegated to the world of classic cars.
Until then, though, the engine in our cars can't operate without them, so here's a video explaining more about the jumping spark that transformed the way the world moves today.