How does the Audi A7 lane-keep assist work?

I've heard a lot about the lane-keep assist feature on the Audi A7. How does this feature actually work and is it reliable?

The Audi A7 lane-keep assist uses a camera to detect lane markings and gently steers your car back into the lane if you start to drift. It works best on well-marked roads and can help improve your driving safety.

The Audi A7 lane-keep assist uses a radar sensor to detect the distance and speed of vehicles in front of you. It then adjusts your speed and applies brakes if needed to maintain a safe following distance.

I have the Audi A7 and use the lane-keep assist all the time. It works great and has never let me down. Just be sure to keep your hands on the wheel and eyes on the road, as it is meant to assist, not replace your driving skills.