What does Audi A2's start-stop function do?

I've heard that some cars have a start-stop function. What does it do and how does it work in the Audi A2?

The start-stop function in the Audi A2 is designed to save fuel and reduce emissions by automatically shutting off the engine when the car is at a complete stop. It restarts the engine when you release the brake pedal or press the accelerator.

Not only does the start-stop function save fuel and reduce emissions, but it also reduces wear and tear on the engine and starter motor. It's a great feature to have in today's world of high gas prices and environmental consciousness.