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Privacy Sandbox - Topics


Simon Harris 1 feb 2022

Privacy Sandbox - Topics

The Privacy Sandbox is the name Google has given to the suite of initiatives that will power the delivery & measurement of online advertising when third party cookies are removed from Chrome in 2023. One popular form of targeting used in online advertising is called interest based targeting, it allows advertisers to reach people that are interested in certain things like Finance or Fashion. 

On January the 25th 2022 Google announced Topics which will power interest based targeting in Chrome when third party cookies are phased out. Google calls Topics an evolution of their previous proposal for interest based targeting which was called FLoC. 

What Are Topics?

With Topics when you browse the internet Chrome will keep a record of the categories of websites you visit e.g. News. Each week Chrome decides the five categories you are most interested in & adds another at random to boost user privacy it then stores these six interests for three weeks. For the purposes of initial testing there are three hundred & fifty interest groups in total.

In terms of using this information to deliver targeted advertising when you visit a website the AdTech companies that the publisher uses can access the browser’s interest groups via an API. Chrome will return up to three topics, one at random from each of the three weeks of data Chrome has stored. Advertisers can then decide if they want to show an advert to someone with these interests.

How is it Different From FLoC?

Google called Topics an evolution of FLoC which was an initiative designed for the same purposes, but an approach that received a fair amount of negative feedback after its first test.

FLoC did not have predefined interest groups, rather Chrome created groups (Cohorts) browsers that had similar browsing habits using machine learning. There were tens of thousands of groups & AdTech firms were expected to calculate what they thought a Cohort was most interested in. 

FLoC’s approach was not only complicated but it was also potentially poor from a user privacy perspective; the sheer number of Cohorts when combined with other information meant in theory FLoC could be used to track users on an individual basis & they could have even revealed sensitive category information. Topics has fewer larger groups which do not reveal any sensitive information to resolve both these challenges.

Topics: Some Outstanding Questions

Clearly it is positive that Topics will be more respectful of user privacy than FLoC but there are still areas of the proposal that need to be addressed. Interest Groups are built from browsing behaviour which in turn is based on the classification of a publisher's website that Google makes from the site (host) name. Google accepts that this initial classification will be imperfect & how topics are assigned to websites requires discussion. In addition to this it is currently unclear how large portals may have more than three categories will be classified & what recourse there is for a publisher that disagrees with their classification 

Some buyers have commented that on first pass the list of topics appears quite narrow vs the myriad of interest based segments that are based on Third Party Cookies, however it is worth noting that three hundred and fifty interest groups is more than double the number Google currently offers in its own platforms. If Google were to expand this to the IAB Classification it would impact most publishers' ability to sell their audiences & in particular would have a negative impact on niche publishers who can command a premium because advertisers are willing to pay a premium to reach the valuable audiences that visit their content.

What Happens Next

Topics is scheduled to begin testing in H1 2022, with most expecting an origin trial (first test) to happen towards the end of Q1. DPG Media will continue to liaise directly with both the Chrome team & our advertising partners to evaluate all privacy sandbox proposals including Topics whilst doubling down to the consented collection of first party data, which has fewer privacy issues than third party data, works across all browsers / devices / operating systems & maintains greater levels of addressability than other solutions.

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Simon Harris
Programmatic trading expert

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