"In an internal combustion engine, the electronic ignition system is used to ignite air-fuel"
https://themechanicalengineering.com/electronic-ignition-system/
"The spark is responsible for producing flame and in automotive where the chemical energy (air-fuel mixture) is converted into mechanical energy (crankshaft rotation). The spark is essential for this to be achieved."
https://studentlesson.com/electronic-ignition-system-definition-function-working-components/
"The ignition system only works if the spark jumps the spark plug gap at the perfect time. This is why it is so crucial to check the timing of our engines to ensure that the spark jumps the spark plug gap at the exact moment to achieve the ideal combustion event for the engine. “The biggest mistake we see people making involving their ignition system is not understanding timing correctly,” Ryden told us."
https://www.chevyhardcore.com/tech-stories/the-basic-ins-and-outs-of-an-msd-ignition-system/
"one of the very first internal combustion engines ran on a mixture of hydrogen and oxygen—and featured an electric spark ignition mechanism"
https://www.cummins.com/news/2022/01/26/how-do-hydrogen-engines-work