In a widely cited study, MarketingExperiments.com, an online marketing research firm, reported that "as much as 29.5 percent of the clicks in three experimental PPC campaigns on Google were fraudulent.."

If you are participating in a pay-per-click program, click fraud may be depleting your advertising dollars.

What Is Click Fraud?
Click fraud takes place when someone (or automated software) that has no interest in the products or services on the advertiser’s website clicks on the link for a malevolent reason. These illegitimate clicks result in increasing the cost of advertising with no return or benefit to the advertiser.

Who Carries Out Click Fraud?

Affiliates
One source of click fraud comes from unscrupulous affiliates. These affiliates sign up for PPC programs that compensate them on each click. They illegitimately increase the number of clicks on paid listings in order to increase the revenue they earn. They do this by clicking on the links manually; paying others to do this for them, or using automated software programs that will click on the links. Legitimate affiliates can send you large amounts of qualified traffic but the deceitful ones can generate a large number fake clicks depleting your advertising dollars.