system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What do the aperature numbers on the camera mean exactly?

I understand how the settings work. f/2,8 creates a big aperature and f/14 creates a small one.

What I don't understand is that the value's are exactly. 

Given that a smaller number gives a larger result, I assume that it is a fraction. But what is it a fraction of?
gpt
f/16 means one sixteenth, not sixteen. And f/4 is a quarter, not 4.

It uses the focal length of your lens to give you the width of your aperture opening.

So with a 200mm focal length, an f/4 aperture has a diameter of 50mm (i.e. a quarter of 200mm)