The actual shot is simply exposure. Now think about that, you can only see items because there is a reflection. So exposure is how much light is coming back and exposing the camera. Back in the day, it was the film being exposed, now it's sensors.  

The actual shot is simply exposure. Now think about that, you can only see items because there is a reflection. So exposure is how much light is coming back and exposing the camera. Back in the day, it was the film being exposed, now it's sensors.