This is hard to explain but basically on my website i have chitika and amazon advertisements. If someone clicks on my Amazon ads, Amazon stores a cookie and if they buy anything later that day from Amazon i earn the money. But what if they click on an Amazon advertisement, then later on someone on my site clicks on a Chitika advertisement... if a visitor buys something from Amazon will Chitika get the money or will I get the money? This is quite hard to explain... if you don't understand let me know what you don't understand and ill try to explain it better (sorry).