Earlier this year, Google announced a new way for advertisers to reach consumers without using cookies to track them individually across sites and applications. Federated Learning of Cohorts (FLoC) groups an individual with people who have similar interests. The idea is that advertisers will target the herd, as opposed to specific individuals, and users would be able maintain more of their privacy. Currently, advertisers can track individuals by dropping cookies, which are small files, onto those individuals’ devices when they visit a website, and then track them as they continue to browse the internet.

Although FLoC is designed to provide users with increased privacy, industry experts are concerned that this new functionality will have the opposite effect. Digital advertisers are already developing techniques to associate FLoC IDs with other information (such as internet browsing history) to improve the accuracy of existing tracking technology. The visual below illustrates how this technique works. By associating someone with multiple groups, you're theoretically placing them within a much smaller group (i.e. within the center circle where the groups overlap) which makes them easier to identify.

Image credit: DuckDuckGo

Another concern is that FLoC IDs allow companies to more easily harvest information on individuals. That’s because, unlike cookie technology, companies will no longer have to drop a cookie when you visit a site on your web browser  in order to track you. Reading your FLoC ID when you initially visit a site would now give the companies a lot of information right then and there. Essentially, your FLoC ID would constitute an additional data point for advertisers to use to fingerprint you and allow them to track you. It will also potentially make their identifications of you more accurate. Finally, there will be trend analysis of the Google advertising groups its users are assigned to that will help predict their behavior. While Google may have created FLoC to increase users' privacy, digital advertisers plan to leverage it to increase the accuracy of their tracking efforts and make it easier for them to do so.

At this point, it's unclear if Google’s FLoC will increase users' privacy by allowing them to remain anonymous within a group of like-minded individuals or if advertisers will be able to leverage it to develop more effective tracking techniques for marketing purposes.

How to opt out of FLoC

If you don’t think it’s worth it to exchange your personal data in order to receive a more personalized online experience, or if you want to take a wait and see approach before making a decision, then you need to take action. Google users are opted into FLoC by default, so you will need to go into your Chrome browser’s settings and opt out by taking the following steps:

1. Click the menu and select Settings to open (on Windows), or select Chrome and then Preferences (on Mac).
   
   
2. Select “Privacy and Security” in the left panel.
   
   
3. Click “Privacy Sandbox” at the bottom of the Privacy and Security section in the right panel.
   
   
4. On the Privacy Sandbox page, click the “Privacy Sandbox trials” switch to disable this feature (grey indicates the feature has been disabled).

At least for now, it's fortunate that Google allows users to opt out. It remains to be seen whether this holds true after Google deprecates cookies. We'll continue to monitor this situation as it unfolds in the coming months and years. If companies like Google (and its parent company, Alphabet) truly wanted to put privacy first, they would need to look at solutions which don't involve tracking of any kind. If Google is going to re-architect online advertising’s infrastructure, it should embrace privacy by design rather than focusing on the needs of its advertisers.

Further reading:
What does Google do with your data?
Protecting your personal data online