CPA, which stands for Cost per Action, is basically a form of affiliate advertisement that is used by almost all companies throughout the world in order to generate leads for their products. This marketing is done by affiliates who work through their own websites in order to send traffic to
the advertiser?s website for the product of the company. CPA deals with specific forms of marketing which involve pay per click and pay per lead ads.
This book really helps!
I highly recommend you read this one.