Why does the Audi A5 have a quattro engine?

I've heard that Audi is known for its quattro engines, but what makes it different from regular engines?

Audi's quattro engine utilizes a permanent all-wheel drive system, providing better traction and performance in all weather conditions.

The quattro engine has the ability to vary power distribution between the front and rear wheels, allowing for improved handling and stability.

Unlike traditional front-wheel drive systems, the quattro engine can send up to 85% of power to the rear wheels, allowing for a more dynamic driving experience.