The key is turned in the ignition to start a vehicle. This action completes a circuit that allows electrical current to flow from the battery to the starter motor. The starter motor then engages the flywheel, which is connected to the crankshaft of the engine. This causes the engine to turn over and start running.
In some vehicles, turning the key in the ignition also powers other electrical components, such as the lights, radio, and air conditioner.
