A key fob, also known as a key ring or keychain, is a small remote device that allows you to control your car's system without the need for a physical key. Whether you carry it in your hand, pocket, or bag, the key fob will open the door hands-free and start the engine with the same remote control. Keyless entry is designed to make it easier for drivers to lock and unlock their car without having to fumble around for a key. With a key fob, you don't need to worry about carrying a real key around with you.
The device uses radio frequencies to communicate with and control your car, so the days of clinking keys are long gone. You should never connect any other key to the ignition key anyway.