Google's certification policies for third parties
How does Google protect user privacy when working with third-party ads and certified ad networks?
In order to protect our users' privacy, we've developed and implemented comprehensive certification policies for the third parties serving ads on AdSense. These policies outline clearly how cookies can and cannot be used on AdSense and require that those third parties not associate cookies with any personal information about users without users' explicit opt-in. These policies also require that the third parties have a mechanism that allows users to opt out of any cookie, web beacon, or other tracking mechanism set by the advertiser for data collection. For more information about user privacy considerations in the certification process, please review our policies.