After announcing it would end support of third-party cookies, Google introduced an alternative known as Federated Learning of Cohorts (FLoC). Instead of tracking people on an individual level, FLoC would categorize users in groups, or cohorts, based on shared interests.
However, Google delayed the launch of FLoC following pushback from regulators, industry partners, and low adoption rates. This caused Google to shelve FLoC entirely and create a new tracking alternative. Enter: Google Topics.
Here’s what we know about Google Topics – and what FLoC was supposed to achieve.
What the FLoC?
Before we dive into what Topics is, let’s discuss what FLoC was meant to do. FLoC was touted to be a new way for advertisers and websites to show relevant ads to online visitors without tracking users across the internet.
FLoC’s methodology is based on the idea of “safety in numbers.” The API assigns the user to a cohort-based on their recent browsing history. Cohorts are dynamic and update every seven days, so as a user’s interests change, so will their FLoC cohort. Unlike traditional third-party cookies, that browsing data would be stored within the individual’s web browser, keeping that information private.
FLoC privacy issues explained
In theory, because these cohorts consist of thousands of people it becomes difficult to identify an individual user. However, privacy experts didn’t think FLoC offered enough protection. FLoC’s use of cohort IDs left users vulnerable to tracking.
A critical flaw was the lack of protection against organizations combining cohort IDs with other tracking mechanisms to identify users. This information can be used for browser fingerprinting since user-specific variation, like browser type, computer, or language, can be used to distinguish users. When combined with cohort IDs, this data can be used to narrow a large cohort to a much smaller group of people. Another issue was the possibility of identifying individual users from multiple visits to the same website. While cohorts are updated weekly, it could be possible to link users to visits over time.
This criticism led to Google abandoning further development of FLoC for an alternative that addressed these issues. Enter: Topics.
How Topics will work
Like FLoC, the Topics API works within the browser. Each website is assigned to broad categories like “Fitness” or “Travel”– at the moment Google has identified 350 topics with more coming as the process matures.
The browser determines a user’s topics based on their browsing history for that week. Up to five topics are chosen by the browser – including a random topic that’s meant to complicate identification – and will be stored for three weeks. When the user visits a website using the Topics API, the browser will pick three topics (one from each of the previous three weeks) to share with the website and ad networks so they can show a relevant ad. However, the website and its associated ad networks can only access topics related to the website’s topic. So, if a user’s topics are “women’s clothing,” “autos & vehicles,” and “fitness,” a news website may not be able to access that user’s topics for that week.
The difference between Topics and FLoC
Google acknowledge FLoC’s shortcomings and used the negative feedback to develop Topics. Here are some key differences between the two systems:
- Reduced fingerprinting: Topics addresses some key privacy concerns caused by FLoC, namely fingerprinting. Since users are not grouped into cohorts, it reduces the chances of identification.
- Avoids sensitive categories: Topics doesn’t target based on sensitive categories like race, sexual orientation, and religion.
- Offers more user control: Topics will be highlighted in a user’s browser settings, allowing them to see which topics they’re assigned and to remove specific topics from their profile. Assigned topics are also erased when browsing history is cleared and are not available while using incognito mode.
- Permission-based: users can opt-out of the Topics API through Chrome’s Privacy Sandbox settings. Likewise, since the API code needs to be added to the website, website owners can opt-out by not implementing the code.
When will Topics be launched?
There isn’t an established timeline for release just yet. Topics is still undergoing development and testing and will announce a timeline after receiving feedback from industry partners.
Data privacy is rapidly evolving. If you need a quick refresh of some of the changes that’s happened, check out these blog posts: