Click fraud is the act of illegally clicking on pay-per-click (PPC) ads to increase site revenue or to exhaust a business's advertising budget. Click fraud is different from invalid clicks (those that are repeated or made by the ad's host/publisher) in that it is intentional, malicious, and has no potential for the ad to result in a sale.
Click fraud happens with pay-per-click advertising and may involve either a human, a computer program, or an automated script pretending to be a legitimate user and clicking on paid search advertising with no intention of purchasing something.
Click fraud is committed for two main reasons: to reduce competition among advertisers or to generate revenue by gaming the PPC advertising system. For example, Advertiser A can engage in click fraud to use up Advertiser B’s ad budget and space on irrelevant clicks, leaving Advertiser A as the sole advertiser. This is an example of a non-contracting party click fraud.
As another example, a malicious attacker may maliciously attempt to make it look like a publisher is clicking on its own ads, which could cause an advertising network to end its relationship with that publisher thinking that they are acting in bad faith. Since PPC advertising revenue is the primary source of income for some publishers, this practice can put a publisher out of business.
Click fraud may also be committed in some cases simply to vandalize without a particular financial motive or when friends, family, or fans of a publisher click on ads on a website to generate more revenue for the publisher. Both forms can be difficult to detect.