What is the role of the oxygen sensor in an Audi 80?

I am trying to understand the function of the oxygen sensor in my Audi 80. Can someone please explain it to me in simple terms?

The oxygen sensor in an Audi 80 measures the amount of oxygen in the exhaust gases, which helps the engine control the fuel-to-air ratio for optimal performance and emissions control.

Think of the oxygen sensor as the eyes and ears of your Audi 80's engine, constantly monitoring and adjusting the air-to-fuel mixture for the best performance and efficiency.

A faulty oxygen sensor can cause your Audi 80 to run poorly and fail emission tests, so it's important to make sure it's functioning properly.