Amazon launched back in 1994 and, two short years later, they developed their Amazon Associates program. In so doing, Amazon was able to increase exposure to their marketplace by enabling web developers and site owners to work as evangelists for their products. It helped drive more traffic to Amazon while giving these business-minded individuals the opportunity to generate more revenue for their own sites and businesses.
I have a free WordPress website with 1000-2000 visitors/month. I was trying to place Amazon Affiliate ad links last night and failed/flailed mightily. I would paste the links into my posts in the HTML mode, switch to Visual mode, and could see the image. However, every time I tried to save or update the post, the image reverted to the gangly hyperlink. As some suggested, I tried cleaning the links of any formatting from the copy and paste with text edit. No dice.