AdChoices icon is a little icon figuring and served with beahaviorally targeted ads. It’s a self-regulatory initiative of ad industry and it is promoted by IAB and other associations. It is an answer for Federal Trade Commission’s call for "clear and prominent notice" of targeted advertising.
By clicking on AdChoices icon, web users are directed to pages explaining behavioral targeting and have an option to opt-out from this kind on targeting.
At the end of 2012, IAB claimed that more than a trillion of ad impressions was delivered each month on behavioral ad networks.
According to a 2012 University of Pennsylvania study, 21% of web users notice the "AdChoices" icon and according to a Carnegie Mellon University study the majority of web busers misunderstands the icon.
The AdChoices website: