Cost per mille requires only that the publisher make the advertising available on his or her website and display it to the page visitors in order to receive a commission. Pay per click requires one additional step in the conversion process to generate revenue for the publisher: A visitor must not only be made aware of the advertisement but must also click on the advertisement to visit the advertiser's website.
As search engines have become more prominent, some affiliate marketers have shifted from sending e-mail spam to creating automatically generated web pages that often contain product data feeds provided by merchants. The goal of such web pages is to manipulate the relevancy or prominence of resources indexed by a search engine, also known as spamdexing. Each page can be targeted to a different niche market through the use of specific keywords, with the result being a skewed form of search engine optimization.