How does the Audi A4's Quattro permanent all-wheel drive system work?

I've heard that the Audi A4 has a powerful all-wheel drive system, but how does it actually work? Is it always on or can it be toggled on and off?

Audi's Quattro system uses a combination of a center differential and torque vectoring to constantly vary the power distribution between the front and rear axels in real time, providing optimal grip and control in any driving conditions.

The Quattro system is always on, but it adjusts power distribution based on the driving mode you select. In normal conditions, it will send 70% of power to the rear wheels for better handling, but can send up to 85% if needed for improved traction in slippery conditions.

As an Audi A4 owner, I can attest to the Quattro system's impressive performance. It's always on and seamlessly adjusts to any changes in driving conditions, providing a smooth and stable ride.