Click fraud is a new type of Internet scam that targets advertising companies rather than consumers. On pay-per-click advertising, a company publishes a small ad in front pages such as Google or Yahoo, which offer an ad service. The ad is displayed for everybody to see, but the company only pays for advertising if a prospective client clicks on the ad. When that happens, the company is billed and Google or Yahoo get a profit. The price is small, sometimes even one penny per click, but when millions of consumers click on the ad every month, the numbers add up.
Click fraud has taken advantage of the pay-per-click advertising programs by republishing the ads in other web pages. While this in itself is not illegal, the problem is that it becomes quite easy for anybody to set up a fake website and publish a list of links or ads; these ads contribute directly to click fraud by allowing publishers, acting as middlemen, to share revenues directly with Google's AdWords/AdSense programs. Most people committing click fraud are operating such a small con that it goes undetected by companies. Those who are truly trying to profit from click fraud may have complex software programs that trick the company into believing the clicks come from different computers or even different countries.