What is a clock spring in the steering column?

What is a clock spring in the steering column?
A clock spring is a ribbon of wire wound up in a plastic container to allow your steering wheel to turn and all the button's, controls and the air bag to work.
Chrysler used a pancake sized blue plastic thing for years for this.
The shaft your steering wheel mounts too goes through the centre, the underside of the wheel plugs into it and the underside of the clock spring case plugs into the wiring harness.
This is a common failure point in most modern cars.