What is ignition cylinder?

An ignition cylinder, also known as an ignition switch or lock cylinder, is a mechanical device that starts the engine of a vehicle. It's the part where you insert your car key (or in modern vehicles, potentially a key fob or push-button start system with a hidden cylinder). Turning the key or activating the electronic start system engages a series of mechanical and/or electrical components that ultimately allow the engine to crank and start. Essentially, it's the physical lock and the switch mechanism that controls power flow to the starter motor.