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IAB Tech Lab’s Advanced TV Working Group introduces an addendum to Video Ad Serving Template (VAST) to support cookieless attribution reporting for Google Chrome browser Attribution Reporting API.

Moving Away from Cookies for Attribution Reporting

One of the fundamental measurement features of digital advertising is the ability to link a user’s experience with an ad to the user’s later interaction with the advertiser’s product. Specifically, measurement platforms are able to attribute successful interactions (conversions) to the impressions or clicks from particular ads which may have led to those interactions.

Today, this is tracked primarily with third-party cookies. If the same cookie that was recorded with an ad impression from a publisher page is later seen on an advertiser’s site where a user makes a purchase, that conversion can be attributed back to the earlier impression event. However, this type of performance reporting is at risk as third-party cookies are becoming increasingly restricted by browsers.

Google’s Attribution Reporting API for Chrome introduces a cookieless, more privacy-sensitive mechanism for attributing conversion events back to earlier ad serving activity. Using this mechanism, measurement companies can continue to provide advertisers campaign performance data without needing to rely on third party cookies.

However, use of the Attribution Reporting API is less passive than the third-party cookie approach; it requires events like impressions and clicks to be explicitly annotated for registration with the browser. In the case of many ad formats, ad measurement technologies can update their events accordingly. 

Passing Attribution Data in Video

For video ads, responsibility for firing tracking events is handed to a third party using VAST. To support the cookieless attribution feature in VAST, IAB Tech Lab is publishing a mechanism that will enable event URLs to be marked to request registration with the Attribution Reporting API. 

Ad tech companies interested in having their events registered should update their VAST tags accordingly, so that supporting players and SDKs can, when the API is available, register those events with the browser on their behalf.

There are no breaking syntax changes involved, so VAST documents with and without the new attributes will be valid and acceptable. This feature is compatible with all versions of VAST. Player support for the addendum or the availability of the API is passive and reporting of all events is unaffected.

As cookies continue to be phased out, this attribution reporting feature is one of many steps to enabling a safer and more privacy preference-controlled internet.

Jon Guarino
Staff Software Engineer