How does Audi A8's all-wheel steering work?

I've heard that the Audi A8 has all-wheel steering, but I'm not sure exactly how it operates. Can someone break down the mechanics of how this feature works?

The Audi A8's all-wheel steering system uses a combination of electronic sensors and mechanical components to allow the rear wheels to turn in the opposite direction of the front wheels at low speeds for easier maneuvering in tight spaces. It also turns the rear wheels in the same direction as the front wheels at high speeds for improved stability and handling.