An Ignition switch is a switch in the control system of an internal combustion engined vehicle that activates the main electrical systems for the vehicle. Besides providing power to the ignition system components (the starter solenoid

Starter solenoid

A starter solenoid is the part of an automobile which relays a large electric current to the starter motor, which in turn sets the engine in motion...

 and ignition related components such as the engine control unit

Engine control unit

An engine control unit is a type of electronic control unit that determines the amount of fuel, ignition timing and other parameters an internal combustion engine needs to keep running...

, spark coil and distributor) it also usually switches on power to many "accessories" (radio, power windows, etc.).

The ignition system

Ignition system

An ignition system is a system for igniting a fuel-air mixture. Ignition systems are well known in the field of internal combustion engines such as those used in petrol engines used to power the majority of motor vehicles, but they are also used in many other applications such as in oil-fired and...

 is used to ignite the fuel-air mixture in the engine.

The starter system is the ignition system, plus the battery, and starter switch, relay, solenoid & electric starter motor.

The ignition switch usually requires a key be inserted that works a lock built into the switch mechanism. It is frequently combined with the starter switch which activates the starter motor. The ignition locking system may be bypassed by disconnecting the wiring to the switch and manipulating it directly; this is known as hotwiring

Hotwiring

Hot-wiring is the process of bypassing an automobile's ignition interlock and thus starting it without the key. A vehicle owner or thief may implement this process.-Methods:...

.