PORTLAND, Ore. - Click fraud has been called the dark side of online advertising, a type of Internet crime aimed at running up bills and cutting down the competition - one click at a time.

Every time you use Google or Yahoo, there are always links at the top of the list for sponsored sites and they do not pop up there by mistake.

Business owners pay for those links. It's called pay-per-click advertising and for many small businesses, it's a great way to attract new business.

However, there is a down side.

Scott Hendison used pay-per-click advertising for an insurance business.

One day, he noticed his bill was increasing, but there was no increase in actual leads. Someone had been fraudulently clicking on his ad and running up his bill, with no intent on using his services.

The good news is that there are ways to protect yourself:

Keep it local - Search engines have the ability to target advertising at a specific area. It's called geo targeting and it can help you because you are not advertising to the world.

Buy software - You can purchase software to help against click fraud. There are several online sites that provide that service, so you can shop around if you think you may be a victim.