A year ago, DiamondHarmony.com, an online jewelry store, decided that it had outgrown its sole source of advertising, which was eBay. The company added an elaborate marketing effort on search engines that included a pay-per-click advertising campaign based on keywords and phrases. For its trouble, DiamondHarmony became ensnared in click fraud.

Instead of actual prospects, the clicks were coming from fraudulent sources. The fraud, which cost DiamondHarmony $17,000 over seven months, was uncovered through analytical software the company installed from ClickTracks of Santa Cruz, Calif.

Click fraud most commonly happens when renegade partners, who get a portion of the fees earned by a search engine each time a paid link is clicked, deliberately generate excessive clicks with no chance that any of the clicks will result in a sale for the business that is paying for them.

The spurious clicks can be generated through automated programs or by paying people to spend time clicking over and over on a link.