How to enable Audi A5's Pre Sense system?

I recently purchased an Audi A5 and I've heard about its Pre Sense system. How do I enable it and what features does it offer?

To enable Pre Sense in your Audi A5, press the Pre Sense button on the center console. This system offers features such as automatic emergency braking and collision avoidance.

There are two levels of Pre Sense in the Audi A5 - basic and plus. To enable Pre Sense plus, go into the driving settings and select 'Pre Sense plus' under the safety menu.