How does the automatic start-stop function work in an Audi A2?

I've noticed my Audi A2 automatically turns off the engine when I come to a complete stop, and starts it back up when I press the accelerator. How does this feature work and is it beneficial?

The automatic start-stop function in the Audi A2 works by cutting off fuel to the engine when the car is at a standstill in order to save fuel. When the driver takes their foot off the brake, the engine automatically starts back up. This feature is most beneficial in city driving where there are frequent stops and starts.