The starting system consists of battery, ignition switch, safety switch, relay, starter and starter drive gear.  The safety switch is turned on only if the shift is on parking position for automatic transmission or the clutch is pressed down for a manual transmission.  When the ignition switch is turned on with the key, the electric current flows from the battery to the relay (a magnetic switch).  The relay is activated and the larger current flows from the battery to the starter.  The starter then pushes the drive gear forward to mesh with the teeth on the engine flywheel and turn the engine.  Once the key is released, the starter pulls the starter drive gear back away from the flywheel.  The starting is completed.