Adversarial information retrieval aspects of sponsored search

Search engines are commercial entities that require revenue to survive. The most prevalent revenue stream for search engines is sponsored search, where content providers have search engines service their links to users in response to queries or in a contextual manner on relevant Web sites. In exchange for providing this service, content providers pay search engines based on the number of clicks (i.e., a click being a visit by a user to the content providers Web page). This business model has proven to be very effective for the search engines, content providers, and searchers. However, click fraud, a unique form of adversarial information retrieval, threatens this business model and, therefore, the "free search" that has rapidly become indispensable to the daily lives of many people. In this paper, we outline how sponsored search is a unique form of information retrieval - not just a mode of advertising, what is click fraud, how click fraud happens, and what are some possible countermeasuresr.