In his blog, our friend IncrediBILL discussed how search queries affect the ads shown by AdSense on a given site. In other words, the ads you see on a page that you landed on because of a search are potentially different than those displayed if you go directly to the site. While this may surprise you as much as it did IncrediBILL, it's actually a "known secret". Anyone who happens to sit down and read (be sure you're wide awake) the original AdSense patent will discover that the patent mentions that aspect at the very end of the claims list. Let me quote the relevant claims for you. The first claim deals with search engine result pages that link back to a site: The description part of the patent explains it a bit further: The second claim deals with historical search engine data: Again, the description provides more detail: I've often felt that these two claims are overlooked by AdSense publishers in their quest to increase their AdSense earnings. But these two claims clearly show that good SEO techniques to increase the relevance of a page to the search engines will also benefit you with increased ad relevance and higher paying ads.