Why does the Audi A3 have a start-stop system and how does it work?

I've noticed that my Audi A3 has a start-stop system but I am not sure what it does or how it works. Can someone explain it to me?

The start-stop system in the Audi A3 automatically shuts off the engine when the car is idle, reducing fuel consumption and emissions. It starts again when the driver takes their foot off the brake. This technology is becoming more common in vehicles to promote fuel efficiency and reduce air pollution.

The start-stop system in the Audi A3 can be temporarily disabled by pressing a button on the dashboard. This is useful if you are in a stop-and-go traffic situation and don't want the engine to keep shutting off and starting back up.

The start-stop system in the Audi A3 uses a special type of battery called an AGM (absorbent glass mat) battery, which is designed to handle the frequent stop-start cycles. If you need to replace the battery in your A3, make sure it is an AGM battery for proper functioning of the start-stop system.