What does Audi's LKA system do?

I've heard that Audi cars have a Lane Keep Assist (LKA) system. Can someone explain to me what it does and how it works? Does it actually help with driving or is it just a fancy feature?

The Audi LKA system is a driver assistance feature that helps keep the vehicle within its lane on the road. It uses sensors and a camera to detect lane markings and makes small adjustments to the steering if the car starts to drift out of its lane.