a product seller site distributes on a pay for placement basis placed product with purchased product when the purchased product is delivered , where the placed product is associated with the purchased product by at least one specific characteristic . further , the product owners bid or pay a fee to place their product . when the customer purchases a product , a search engine determines which products from a database of products available for placement meet the search criteria and offers to distribute the placement product with the purchased product . the search criteria comprise matching the purchased product with similar products to be placed with the purchased product and finding the highest bidder or fee from the group of matching placement products .