What is Audi A7's active lane assist and how does it work?

I am planning on purchasing an Audi A7 and I have heard about its active lane assist feature. What is it and how does it work?

Audi A7's active lane assist is a safety feature that uses a camera mounted in the rearview mirror to detect lane markings and monitor the vehicle's position in the lane. Once activated, the system will gently steer the car back into its lane if it detects that it is drifting out of the lane without the turn signal activated.

Active lane assist can also help reduce fatigue on long drives by automatically adjusting the steering to keep the vehicle centered in the lane.