How does the Audi A1's active lane assist system work?

I heard that the Audi A1 has an active lane assist system that can help with lane keeping. How does this feature work and is it reliable?

The Audi A1's active lane assist uses a front camera to monitor lane markings and alerts the driver if the vehicle starts to drift out of its lane. It can also make subtle steering corrections to keep the car in its lane.

I've found the active lane assist in the A1 to be very reliable. However, it's important to note that it is not a substitute for attentive driving and should only be used as a support system.