Making money online through Adsense and other ad networks

Oftentimes, some of my sites with high traffic but low CTR rates are showing AdSense earnings even without any clicks showing on the AdSense earnings report. Got the same experience?

This concern has just been clarified today by the AdSense blog. It seems like the earnings come from CPM ads. CPM ads or cost-per-impression ads are ads that ad units will display when advertisers bid specifically on your site using site targeting , and for those ads you'll generate earnings with each valid impression.

It should also be noted that CPM earnings are not the same as the values seen in the eCPM column. The eCPM is only a reporting feature that to help in comparing ad performance.

via Inside AdSense