Google’s latest attempt to replace cookie-based advertising is to use Chrome to determine a handful of topics that interest you, then send one randomly to ad networks.
The ad personalization approach is called “Topics API” and its purpose is to replace tracking cookies in Chrome with a privacy-preserving alternative.
The new system addresses the number of websites and advertising networks that use a variety of cookies and computer scripts to track your browsing history for the purpose of serving you targeted advertisements. Advertising-based monitoring is why other browsers such as Apple’s Safari and Mozilla’s Firefox have gone out of their way to block third-party cookies by default to protect user privacy.
Google, on the other hand, has tried to contain cookies without disrupting online advertising, a key revenue generator for the company. In 2019, Google pioneered this with FLoC or Federated Learning of Cohorts, which offered to deliver relevant ads to users by tracking their activities in an aggregated format. Users would be placed in groups of peers who are like-minded and interested in the same topics. In turn, Google’s Chrome browser would assign each cohort an ID, which websites could use to determine which ads to show.
“This approach effectively hides individuals ‘in the crowd’ and uses on-device processing to keep a person’s web history private on the browser,” Google wrote one year ago.
But not everyone was a fan of the plan. the Electronic Frontier Foundation privacy group and the creators of the Vivaldi The browser argued that Google’s FLoC idea could still share sensitive user information with advertisers via cohort IDs.
“They can see that every person buying certain medical products seems to belong to (FLoC) group 1324, or 98744, or 19287,” Vivaldi wrote in a blog post last year. “So if you have one of those FLoC IDs, they may show ads for that product – even if that particular medical condition is something you’d rather keep to yourself.”
In response to feedback, Google has developed the Topics API, which will replace the original FLoC proposal. Perhaps the biggest change is how it removes clustering users by cohort ID. Instead, the system simply uses on-device processing to select up to five topics that Google thinks you’re interested in based on your recent Chrome browsing history.
Topics assigned to your browser also promise to be viewable in Chrome unlike third-party cookies.
Topics include things like “sports”, “fitness”, “travel”, “rock music”, and “news”. Chrome will then share a total of three topics, one for each of the last three weeks, with the websites and ad partners you visit, providing a data point they can use to serve a relevant ad.
“Topics are only kept for three weeks and old topics are deleted. This process takes place entirely on your device without involving any external servers, including Google servers,” the company said. “Most importantly, topics are carefully selected and will not include potentially sensitive categories, such as gender or race.”
During a media roundtable, Chrome product manager Ben Galbraith also explained how the company introduced safeguards to prevent websites from abusing the Topics API to profile and “fingerprint data” a user’s web habits, which was a major concern with Google’s FLoC proposal.
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“The topic returned to the calling website—one of five topics—is chosen at random. And the site that requests it always gets the same topic for that week,” he said. “Other sites will receive different combinations of these topics, so that’s something we’ve done to harden ourselves against the potential for abuse.
The other notable part is how Chrome users can opt out of the Topics API system, although this doesn’t necessarily prevent website publishers from using other means to serve targeted ads. In the first stages, Google plans to use 350 topics. The company may expand the list of topics, but it won’t go beyond the “small thousands”, according to Galbraith.
It’s also important to note that the Topics API system will only work for sites that decide to participate. Nonetheless, Google hopes the system will give advertisers a viable option to deliver relevant ads instead of resorting to more covert and invasive ad tracking technologies.
Google plans to first introduce the Topics API in a developer trial later this quarter, which will help determine how accurately the new system can serve targeted ads or if it has any unforeseen flaws. The company will then use the feedback to improve the API for potential rollout as Google prepares to block third-party cookies in Chrome in mid-2023.
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