Google Topics replaces FLoC as new targeting tech tool

On 25 January 2022, Google announced a new Privacy Sandbox proposal, Topics.

And with it, the death of FLoC (Federated Learning of Cohorts), its controversial project to replace cookies for interest-based advertising that identifies you based on your “cohort,” or a group of people that share similar interests.

This is after a year of growing negative policy and industry feedback, or as Vinay Goel, Product Director, Privacy Sandbox, Chrome, puts nicely in his blog post announcement, “Topics was informed by our learning and widespread community feedback from our earlier FLoC trials”.

What the FLoC is going on here?

To deal with the impending death of the third-party cookie, Google announced Privacy Sandbox in August 2019 as “a set of open standards to fundamentally enhance privacy on the web”.

Essentially, as Google puts it, Privacy Sandbox is a “series of proposals to satisfy third-party use cases without third-party cookies or other tracking mechanisms”, with Topics now replacing its previous proposal, FLoC.

Continuing its Privacy Sandbox efforts, Google announced FLoC (Federated Learning of Cohorts) in March 2021 as a new piece of Privacy Sandbox web technology for interest-based advertising that was “a new approach to interest-based advertising that both improves privacy and gives publishers a tool they need for viable advertising business models”.

FLoC was designed to help advertisers perform behavioural targeting without third-party cookies.

A FLoC-enabled browser would collect information about its user’s browsing habits.

Users with similar browsing habits would then be grouped into the same cohort. Each user’s browser will share a cohort ID, indicating which group they belong to, with websites and advertisers.

That being said, FLoC has not been received well by the industry, with the Electronic Frontier Foundation poking holes at its privacy issues and every other major browser declining its use.

In comes Topics

Example illustrations of third party cookies vs Google Topics
Example illustrations of 3rd party cookies (left) vs Topics (right). Image via Google

Google explains that “With Topics, your browser determines a handful of topics, like “Fitness” or “Travel & Transportation,” that represent your top interests for that week based on your browsing history.”.

When you visit a participating site, Topics picks three topics (one from each of the past three weeks) to share with the site and its advertising partners. Topics are selected from your device with no involvement from external servers, including Google servers, and they are only kept for only three weeks. Old topics will be deleted. Topics are selected from an advertising taxonomy with about ~350 initial topics in total for the API design. Sensitive categories such as gender or race are excluded from curation.

Essentially, Topics is an API that uses your browsing history to deduce your broad topic interest, such as, fitness.

You, the user, have control over what topics you want to share with the API. It will then compile and share different sets of data points of your interests every week with advertisers, who can then use the data to serve targeted interest-based ads.

Google Topics API lifecycle
The Topics API lifecycle. Image via Chrome Developers

What’s the difference between FLoC and Topics?

The differences between FLoC and Topics lie between usage, retention, and data and fingerprinting.

Some might say Topics is merely a rebrand of FLoC. We’re inclined to agree. However, for the sake of brevity (click on the links shared in this entire article for a deeper understanding), let’s look at these three key areas where FLoC differs from its replacement, Topics:


In its initial experiment, FLoC automatically included browsing activity from sites with ads on them. With Topics, sites will have to use the API to be eligible for generating users’ topics.


FLoC cohorts will be re-calculated on a weekly basis, each time using data from the previous week’s browsing. Topics API conducts weekly calculations on topics being associated with a user, with the topics kept for only three weeks.

Data and fingerprinting

FLoC shares a cohort ID whereas Topics selects three topics to share with websites and advertisers.
So while “FLoC added too much fingerprinting data to the ecosystem”, Topics is attempting to reduce this by introducing 5% noise to add some randomness, “making it harder for sites to cross-correlate the same user”.

What does this mean for advertisers and brands?

Not much at this point, really. Topics API is very new and is still being discussed and updated as we speak.

“I think FLoC being replaced by Topics is a step in the right direction for targeting the right users in the cookies world, but it’s still not perfect as the topic grouping is quite broad. Google has only announced 350 groups, and they’re broadly defined – ‘Sports’, ‘Music’. Topics will force media buyers to be more proactive with generating clear ad messaging and engaging creative regularly. This is the first iteration of Topics, and I’m sure Google will develop more granular groupings.” – Will Chalk, Head of Google Performance and Customer Analytics, Leaf

One big disparity between FLoC and Topics as Brave states is that, “In FLoC, all advertisers would learn the same interests for each user. In the Topics API, an advertiser “only” learns user interests and behaviours for the pages on which that advertiser appears.”. This puts larger advertisers like Google at an advantage.

Current topics in Topics API design are limited, and we all know that broad targeting does not usually lead to better ad performance. This means less control for the advertiser.

Not only that, adoption is also limited to the Chrome browser for now, and probably in the long run, so this means that there will be a lack of cross-browser data and support.

Google has also yet to launch the developer trial of Topics in Chrome that includes user controls, and enables website developers and the ads industry to try it out.

Time will tell for sure. We will continue to update this article when we have more information.

Stay tuned!