Google plans to stop selling ads based on tracked browsing history

Google says its new approach will enhance privacy, but critics say it moves essential parts of the open web into the firm's walled garden

Google plans to stop selling ads that rely on users ' web browsing history - a move that could help push the digital advertising industry away from the use of individualised tracking, as calls grow for more privacy online.

Last year, the internet giant said that it would phase out support for third-party cookies by 2022. Once these cookies are gone from Chrome, Google will neither create nor use any alternative user-level identifiers in its products to track people as they browse across websites.

However, Google says its announcement only covers its ad tools and unique identifiers for websites, not mobile apps, so a major part of Google's digital ad ecosystem will not be affected.

"If digital advertising doesn't evolve to address the growing concerns people have about their privacy and how their personal identity is being used, we risk the future of the free and open web," David Temkin, Google's director of product management for ads privacy and trust, wrote in a blog post.

Temkin said that such user-level identifiers are unlikely to meet growing expectations for user privacy. They will not "stand up to rapidly evolving regulatory restrictions," and "therefore aren't a sustainable long term investment."

"People shouldn't have to accept being tracked across the web in order to get the benefits of relevant advertising."

Temkin added that Google's web products in the future would be powered by APIs that would prevent individual tracking, while still delivering results for publishers and advertisers: part of its push toward a Privacy Sandbox plan.

As part of the new scheme, Google proposes storing and processing all user data in the web browser, and using machine learning algorithms to assess users' interests and target them with relevant ads.

Google will present the data to advertisers in the form of a cryptographic token, which will obfuscate identifying information. Thus, advertisers will be able to target ads without directly identifying individuals.

Critics, however, warn that the scheme will place many features of the open web under Google's control.

In November last year, the Marketers for an Open Web (MOW) - an alliance of technology and publishing companies in the UK - filed a complaint with the Competition and Markets Authority, urging the regulator to delay the rollout of Privacy Sandbox technology.

The MOW said that delaying Privacy Sandbox will give regulators time to formulate 'long term competitive remedies to mitigate [Google's dominance]'.

The group argues that the proposed changes will move the digital advertising business 'into the walled garden of [Google's] Chrome browser, where it would be beyond the reach of regulators'.

Google maintains that Federated Learning of Cohorts (FLoC) - its privacy-enhanced solution for serving targeted advertisements - could be an effective way to take third-party cookies out of the advertising equation.

Temkin says that FLoCs will hide individuals within "large crowds of people with common interests." Google intends to make FLoC-based cohorts available for public testing through origin trials with its next release this month. Testing with advertisers in Google Ads is expected to start in Q2.