Click Fraud
  
How could a simple click result in fraud? Well, it all starts with pay per click (PPC) advertising. As you'll probably guess from the name, the amount of revenue these ads generate relies on the number of clicks they produce. More clicks, more money. So, by pumping up the number of clicks an ad receives, the publisher generates additional revenue.
An illegal practice, the fraudster could sit and repeatedly click on a website’s banner ads or hyperlinks, or better yet use automated software or online “bots” to do it. Sometimes it’s the advertiser’s competitors who want to run up the victim’s advertising costs and others do it to increase revenue for banner ads they sell. It can be prevented by using firewalls and blocking tools. There are also monitoring systems to check every ad click to see if it appears to be excessive or from a competitor or otherwise suspect.