Banner Ads in apps

Hello,
I have just started developing games for iOS and Android with unity, and i have begun playing around with ads in my game. However what I think almost all of the ad networks fail to mention is how exactly you earn the money from the ads: in banner ads do you get paid more the longer the ad is present, and do you only get paid if a user presses an interstitial ad?
I guess this is different for each network but I am planning on using admob, so if somebody could tell more about this one it would be greatly appreciated

Andy

 

I'll just leave this here

In most cases you just get payed for clicks. The longer the ad is up the more likely it is to be clicked.

 

Hmm I believe I read somewhere else that it is not true for Admobs, can someone confirm that?

 

Based on their glossary, I think they pay per acquisition, per click, and per thousand impressions depending on the advertisement. Their site isn't exactly the easiest thing to really browse through.