What is the quattro all-wheel drive system and how does it impact the performance of Audi A5?

I've heard about Audi's quattro all-wheel drive system and how it is a major selling point for the A5. Can someone explain in detail what this system does and how it affects the car's performance?

The quattro all-wheel drive system is a technology developed by Audi that distributes power to all four wheels of the car, providing better traction and control on various road conditions. This helps the A5 deliver a smoother and more stable driving experience, especially in adverse weather conditions.