How does the Audi A5's Quattro system improve stability and handling in poor weather conditions?

I've heard that the Audi A5 has a Quattro all-wheel drive system, but I'm not sure how it works and if it's really necessary. Can someone explain the benefits and impact on driving in rain, snow, or other challenging conditions?

The Quattro system distributes power between all four wheels, providing better traction and control in slippery conditions, such as rain or snow. It also helps improve overall stability and cornering performance.