Your C4 Corvette's ignition switch allows the battery to send a powerful surge of electricity to the starter when the car is being started. Without this switch in good working order, there's a good chance that you're car won't start.
This switch also allows you to control many of the car's accessories when the car is parked, while preventing accessories from running down the battery. Sometimes located on the dash or steering column, installation can be easy with basic mechanical knowledge and hand tools.
Always reference your service manual before tackling an electrical project.