By Clare Newman


In August 2019, in a bid to replace third party cookies Google announced a new initiative to enhance privacy on the web – the Privacy Sandbox. The first implementation of which was the Federated Learning of Cohorts, or FLoC for short. The technology grouped together people with similar browsing histories, then allowed advertisers to target those groups of people (the “cohorts”) without most of the personally-identifiable information that cookies usually provide. Although an improvement compared with third-party cookies, it has not proved popular with many privacy advocacy groups and companies.

© Image by Google
Cookies (left) compared to Topics (right), which Google says will be easier to manage and understand

Hampered by regulatory attention and a delay to the implementation timeline by up to a year, Google said that the switch would not now happen until the second half of 2023.

However, yesterday Google announced that it is changing its plan, replacing the FLoC proposal with a new technology, called the Topics API.

Asked why the company decided to introduce a new solution, Google senior director for product Ben Galbraith acknowledged privacy concerns with FLoC and said Topics was easier for users to understand. He also said Topics would make it easier for Google to remove sensitive topics from being used to target users. Galbraith noted that Topics was informed by learnings and advertising industry feedback from earlier FLoC trials.

Similar to the earlier FLoC design, Topics uses your browser to locally generate groups that advertisers can target, but now it’s based on specific topics instead of grouping people that share an interest in multiple topics together.

Here’s how Google explains it:
With Topics, your browser determines a handful of topics, like “Fitness” or “Travel,” that represent your top interests for that week based on your browsing history. Topics are kept for only three weeks and old topics are deleted. This process happens entirely on your device without involving any external servers, including Google servers. When you visit a participating site, Topics picks just three topics, one topic from each of the past three weeks, to share with the site and its advertising partners. Topics enables browsers to give you meaningful transparency and control over this data, and in Chrome, we’re building user controls that let you see the topics, remove any you don’t like, or disable the feature completely.

Although it may still be possible to match these different Topics to build up a pretty solid user profile and match it to real-life individuals, Google plans to make that difficult by not giving websites the full picture. Instead of giving each site all of a user’s Topics, Google will give it only three, one each selected randomly from each weekly set of five generated over the past three weeks.

Developer trials begin in a couple of months, and user trials are still a long way off so it could be Topics will replace third-party advertising cookies in Chrome by the end of next year.

Galbraith concluded that Google hadn’t decided yet whether Topics will be opt-in or opt-out for end users. It will be interesting to see how this approach evolves in the market.