So what is Click Fraud? Well - since the dawn of PPC, people have been trying to cheat with PPC - web site owners who show Adsense adverts might get their friends to click on their adverts in order to earn revenue. Or your competitor might repeatedly click on your adverts to use up your budget. These "clickers" might be outsourced (as reported in India Times article "India's secret army of online ad clickers.") or they might be automated bots.

BUT..

Before you start worrying - If you have a 1st tier PPC provider such as Google, Yahoo or MSN then you probably don't really have to worry about click fraud as they are pretty hot at detecting invalid clicks. The issue is widely conceieved to be more of a problem with some of the 2nd and 3rd tiered PPC engines.

If you're still interested in making sure that you're not suffering though - here are some things to look out for.

• Look at your log files - are you getting lots of clicks from the same IP address?
• Have your clicks increased significantly with no related increase in conversions.
• Has your Click Through Rate increased significantly?
• Look at your web stats - look for things like increased bounce rate, shorter length of visits, increased visits from the same type of browser or operating system.
• Increased clicks from overseas.

And if you're still worried - contact your PPC provider and report your concerns.