How does the Audi A1's start-stop system work?

I've heard that the Audi A1 has a start-stop system, but I'm not exactly sure what that means. Can someone explain how it works?

The start-stop system in the Audi A1 automatically shuts off the engine when the vehicle is at a complete stop, such as at a red light or in traffic. This helps save fuel and reduce emissions. To restart the engine, simply release the brake pedal and the engine will automatically restart.

The start-stop system in the Audi A1 is designed to improve fuel efficiency by reducing idle time. When the vehicle comes to a stop, the engine shuts off and then restarts when you lift your foot off the brake pedal. It may take some getting used to, but it's a great feature for city driving.

The start-stop system in the Audi A1 can be manually turned off by pressing a button on the centre console. This can be useful in heavy traffic or for situations where you may not want the engine to shut off, such as when using the air conditioning.