Cookie stuffing, also known as cookie dropping, is a technique used in affiliate marketing. It involves dropping a third-party cookie from a website thats not related to the one that the user has visited. Because it happens without the agreement of the user, this technique is considered controversial. Actually, some affiliate networks prohibit cookie stuffing and even blacklist the affiliate partners who use this technique. This is because cookie stuffing does not encourage the visitors to become paying customers. Instead, it tricks the merchant into thinking that the user (with the cookies on the computer) has made the purchase through the affiliate link of the cookie stuffer.