Click fraud is a type of fraud that occurs on the Internet in pay-per-click (PPC) online advertising. In this type of advertising, the owners of websites that post the ads are paid based on how many site visitors click on the ads. Fraud occurs when a person, automated script, computer program or an auto clicker imitates a legitimate user of a web browser, clicking on such an ad without having an actual interest in the target of the ad's link in order to increase revenue. Click fraud is the subject of some controversy and increasing litigation due to the advertising networks being a key beneficiary of the fraud. Media entrepreneur and journalist John Battelle describes click fraud as the intentionally malicious, "decidedly black hat" practice of publishers gaming paid search advertising by employing robots or low-wage workers to click on ads on their sites repeatedly, thereby generating money to be paid by the advertiser to the publisher and to any agent the advertiser may be using. Pay-per-click advertising PPC advertising is an arrangement in which webmasters (operators of websites), acting as publishers, display clickable links from advertisers in exchange for a charge per click. As this industry evolved, a number of advertising networks developed, which acted as middlemen between these two groups (publishers and advertisers). Each time a (believed to be) valid Web user clicks on an ad, the advertiser pays the advertising network, which in turn pays the publisher a share of this money. This revenue-sharing system is seen as an incentive for click fraud. The largest of the advertising networks, Google's AdWords/AdSense and Yahoo! Search Marketing, act in a dual role, since they are also publishers themselves (on their search engines). According to critics, this complex relationship may create a conflict of interest. This is because these companies lose money to undetected click fraud when paying out to the publisher but make more money when collecting fees from the advertiser. Because of the spread between what they collect and pay out, unfettered click fraud would create short-term profits for these companies. Non-contracting parties A secondary source of click fraud is non-contracting parties, who are not part of any pay-per-click agreement. This type of fraud is even harder to police, because perpetrators generally cannot be sued for breach of contract or charged criminally with fraud. Examples of non-contracting parties are: Competitors of advertisers: These parties may wish to harm