How does the auto start-stop function work in the Audi A1?

I'm curious about the auto start-stop function in the Audi A1. Can someone explain how it works and if it is effective in saving fuel and reducing emissions?

The auto start-stop function in the Audi A1 automatically turns off the engine when the car is at a complete stop, such as at a traffic light. The engine will then automatically start back up when you release the brake pedal.

This feature helps improve fuel efficiency by reducing the amount of time the engine spends idling. It also helps reduce emissions and can save you money on gas in the long run.