Traffic trading terms
 

Hey,

Maybe you can help me with a simple question.
In traffic trading, what is the difference between "in", "out" and "clicks"?

"In" and "out" are pretty clear to me, but I don't understand what "clicks" are for. Are they for outgoing traffic... incoming? Clicks on what, on toplist links? I can't find a traffic trading script that has these terms explained. I'm using tradex right now and all these 3 stats are displayed.
Thanks