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The Evolving Programmatic Identity Landscape

Garrett McGrath, Senior Vice President, Product Management

March 19, 2024 | 4 min read

As third-party cookies crumble, the way advertisers identify web users is undergoing a transformation. New solutions like Universal IDs and ID “Bridging” are emerging in this cookieless future – however, these new solutions bring challenges around transparency and responsible application.  

The OpenRTB definition of the “buyeruid” parameter has been around for many years. This value is defined as a “Buyer-specific ID for the user as mapped by the exchange for the buyer.” For a long time, it’s been functionally understood that “buyeruid” means the DSP’s cookie. You know the drill – SSP and DSP perform a cookie sync; then, the SSP sends the DSP’s cookie back to the DSP at auction time. This lets the DSP look up the user in their system and decide how to bid (or if they should bid at all).

For web transactions, this cookie value in the DSP’s system lets them recognize the user, which is key to ad targeting (i.e. personalization) and then frequency capping. It also allows the DSP to measure their ads’ performance through attribution and measurement. Think of it as understanding the return on ad spend.

Enter Universal IDs and the Rise of EIDs

With third-party cookies on the way out, new ID solutions are popping up, often called Universal IDs. These typically utilize a publisher’s first-party cookie as the method for providing browser persistence. OpenRTB handles these through a separate array called Extended IDs (“EIDs”) – completely different from the old “buyeruid.”

DSPs are normally built to prioritize the “buyeruid” value for bidding. It’s part of their standard practice. The “EIDs” array on the other hand, is a bit of a wild card. Some DSPs might use it more than others, but it almost always is lower priority to a “buyeruid” when that value is present, due to existing third-party cookie targeting methods which are far more mature than using “EIDs.” “EIDs” are a future-looking technology however they have a bit of a cold start problem until third-party cookies truly go away.

Two Sides of the Coin: Transparency Is Key

Recently, the industry has observed certain buyer-specific identifiers in the programmatic bidstream in sometimes unexpected locations. For example, a cookie sync value in “buyeruid” (which is generally expected), however, for a browser that does not utilize third-party cookies so, in this case, unexpected. This practice has been referred to as ID Bridging.  

The potential positives of these new identifiers are obvious, as they provide DSPs a chance to better address non-cookie requests, like those that come from Safari or Firefox.

However, if there is a lack of transparency in how the ID is derived, it creates a potential negative reaction, as the DSP may think the identifier represents something that it does not. 

ID Bridging: A Potential Solution 

ID Bridging could be useful provided the identification techniques used are clearly understood, the DSPs know it’s happening, and consumer notice/choice is respected. With these important caveats, ID Bridging could be used to make unaddressable inventory addressable.

However, if ID Bridging is occurring non-transparently to DSPs and without proper consumer notice and choice, it is problematic and potentially misleading. 

It’s also important to understand the provenance of any given ID and how it was created. Some ID providers have written agreements with DSPs specifying how their IDs are generated; others do not. In either case, there needs to be a clear understanding of how an ID is created and that the expectations of all parties are clearly understood.

For Magnite, there could be value in ID Bridging, provided that – if and only if – all parties between seller and buyer clearly understand what is happening. With proper signaling and transparency it should be up to the buyer to decide how to treat such IDs. For example, it is conceivable that a buyer might want to use such identification techniques for higher funnel branding campaigns but perhaps less so for performance due to the after-impression tracking impacts. In any event, buyers must have the proper real-time information to make such decisions and not be subject to “surprise” implementations.

Tags: Buyer, Identity

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