Until now, AdSense publisher were taking the advantage of “contextual and placement-targeted” advertising. Now, Google has introduced “interest-based advertising,” that will associate categories of interest to show you more relevant text and display ads. To develop interest categories, we'll recognize the types of webpages users visit across the AdSense network.
Users browsing the web will benefit from the additional relevancy that interest-based ads can provide. And by visiting the new Ads Preferences Manager, users can see what interest categories we think they fall into, or add and remove categories themselves. The Ads Preferences Manager can be found by clicking on most "Ads by Google" links you see on Google ads throughout the web.
Please ensure that your site's privacy policies are up-to-date to reflect the use of interest-based advertising by April 8, 2009. Users can also choose not to be part of this advertising cookie which they can do so by using a plug-in that maintains their opt-out choice on their browser.