Search Engine Marketing and Click Fraud

Since its introduction the Internet began a rapid advance into all areas oflife and changed the working world as well as daily life. The Internetprovides a vast amount of information for almost every topic. Since the endof the 20th century, so called search engines established oneself to retrieveinformation online. After inserting one or several search terms, the searcherreceives a list of search results ordered by certain relevance criteria of thesearch engine algorithm.The individual search terms indicate an interest of the searcher for a certaintopic. The selective approach at a point in time when the potential targetaudience is already thematically activated and involved represents anattractive opportunity for advertisers and led to the inclusion ofadvertisements besides the search results of a conducted search.This search engine advertising has become a dominant form of onlineadvertising and is the predominant business model of search engines. Theworld-wide leading search engine Google earned 16 billion US $ withsearch engine advertisement in the fiscal year 2007. The advertiser does notusually pay for the impression of the ad, but for a click on theadvertisement.Fraudulent clicks present an inherent problem of this so called pay-per-clickmodel. Click fraud represent any procedure that illegally exploits pay-perclickmarkets. In particular, click fraud resolves around intentional clickswithout intent to interact with the advertiser.In this context, a class action against several search engine providers in2005 attracted attention (DELANEY 2005). To what extend, search engineproviders are liable for the manipulation of clicks and click rates, was notfinally judicially clarified. Google settled the class action by agreeing topay its advertisers 90 million US $.1Click fraud represents a general threat for the pay-per-click model as wellas a more specific threat for the business model of search engines. Searchengine providers need to ascertain the reliability and correctness of the payper-click model to preserve