Sorry Guys.. another Newb question..

[ProMedia]

I've been on this forum for two months. I really find it educational. Great stuff from Servando, Luke and others.
I'm getting close to taking action.

Just a few more dumb questions... LOL

Has anyone used click.org for tracking? I haven't seen any other tracker sites that have bothered to fully explain their stuff. I guess is they assume we all know the basics. I don't. I'm coming over from Selling on Amazon to this.
Click.org looks good to this newbie but.. I don't know what I don't know.

• I'm going to use Peerfly for offers.
• I'm going to use Purelander for landing pages - Totally love the ripper feature!
• I'm thinking Click.org for tracking.
• I'm going to serve my Landers from Amazon CloudFront. - But I'm wondering why not just serve from S3? It seems to work.

What I still don't understand: What the hell is a "postback URL?" I've heard them talked about for a long time (15 years).
I have them on my WP backend on my 20 blogs. But never used them because no one has ever explained them. And when I say explained, I mean by someone who speaks a language other than millennial-speak.