This "heat map" illustrates the ideal placing on a sample page layout. The colors fade from dark orange (strongest performance) to light yellow (weakest performance). All other things being equal, ads located above the fold tend to perform better than those below the fold. Ads placed near rich content and navigational aids usually do well because users are focused on those areas of a page.
While this heat map is useful as a positioning guideline, we strongly recommend putting your users first when deciding on ad location. Think about their behavior on different pages, and what will be most useful and visible to them. You'll find that the most optimal ad position isn't always what you expect on certain pages.
Also, placing ads to the left side of your page seems to work better almost all the time. Of course, this is logical because text is generally written from left to right (unless you come from certain countries where it's the other way around).
People will finish a sentence and return their eyes to the left position, which means they have a higher chance of spotting your ads.
