Google’s Interest-Based Advertising

googleAs an owner and marketing agency for several websites, I employ Google’s AdSense service to automatically supply advertising on them. It’s a good service, especially as a backup to my primary ad serving vendors for inventory that doesn’t get filled. By the way, I’m a big fan of many of Google’s services and admire their innovation… and then I learned of this.

Google has been working on a new approach called, Interest-Based Advertising. The simple explanation is they build a profile on you and then present advertising to you that matches your interests. Here’s an abridged email I received from Google that may help explain this.


We’re writing to let you know about the upcoming launch of interest-based advertising, which will require you to review and make any necessary changes to your site’s privacy policies.

Interest-based advertising will allow advertisers to show ads based on a user’s previous interactions with them, such as visits to advertiser website and also to reach users based on their interests (e.g. “sports enthusiast”).  To develop interest categories, we will recognize the types of web pages users visit throughout the Google content network.  As an example, if they visit a number of sports pages, we will add them to the “sports enthusiast” interest category.

As a result of this announcement, your privacy policy will now need to reflect the use of interest-based advertising. Please review the information here to ensure that your site’s privacy policies are up-to-date, and make any necessary changes by April 8, 2009.  Because publisher sites and laws vary across countries, we’re unfortunately unable to suggest specific privacy policy language.

We appreciate your participation and look forward to this upcoming enhancement.


The Google AdSense
1600 Amphitheatre Parkway
Mountain View, CA 94043

So how are they doing this? Basically, they are dropping a cookie on your computer when you visit sites displaying Google ads which begins collecting, storing and transmitting your viewing habits back to Google so they can build a profile on you. Are you feeling a little violated yet? Here’s their explanation:

The DoubleClick DART cookie is used by Google in the ads served on the websites of its partners, such as websites displaying AdSense ads or participating in Google certified ad networks. When users visit a partner’s website and either view or click on an ad, a cookie may be dropped on that end user’s browser. The data gathered from these cookies will be used to help better serve and manage ads on the publisher’s site(s) and across the web.

What should I put in my privacy policy about the DoubleClick DART cookie?

Your posted privacy policy should include the following information about Google and the DoubleClick DART cookie:

  • Google, as a third party vendor, uses cookies to serve ads on your site.
  • Google’s use of the DART cookie enables it and its partners to serve ads to your users based on their visit to your sites and/or other sites on the Internet.
  • Users may opt out of the use of the DART cookie by visiting the Google ad and content network privacy policy.

If you have not opted out of third-party ad serving, the cookies of other third-party vendors may also be used to serve ads on your site, and should be disclosed in your privacy policy as well.

Because publisher sites and laws across countries vary, we’re unable to suggest specific privacy policy language. However, you may wish to review resources such as the Network Advertising Initiative, or NAI, which suggests the following language for data collection of non-personally identifying information:

We use third-party advertising companies to serve ads when you visit our website. These companies may use information (not including your name, address, email address, or telephone number) about your visits to this and other websites in order to provide advertisements about goods and services of interest to you. If you would like more information about this practice and to know your choices about not having this information used by these companies, click here.

You can find additional information in Appendix A of the NAI Self-Regulatory principles for publishers (PDF). Please note that the NAI may change this sample language at any time.

Funny thing, well not really, but I noticed a few months ago that I was being “profiled.” Meaning, if I clicked on a Google ad on my site to go to that site, I then noticed that ads for that site began to follow me around to other sites. And, since I’m in quite a bit, their ads follow me all around.

So I did a little test. I picked the topic of “skin care” and began to visit and click around these type websites to create new profile for myself. As early as the following day, their ads began to appear on my sites that employed Google AdSense.

Okay, enough with the fun and games. Where does this end? Will Google also collect and build profiles based on content in Gmail, Google Bookmarks and other Google services? And could they be subpoenaed to share this information? Time will tell but in the meantime, be careful where you surf. According to Google, you are what you view.

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