What Does Audi's Lane Departure Warning System Do?

I recently purchased an Audi A1 and noticed it has a Lane Departure Warning System. Can someone explain what this feature does and how it works?

The Lane Departure Warning System uses sensors and cameras to detect if your vehicle is drifting out of its lane without signaling. It will then alert you with visual and audible warnings to steer back onto the correct lane.

This safety feature is especially useful on long drives or when you may be getting tired. It can help prevent accidents by reminding you to stay in your lane.