Linked audiences

Posted on Wednesday 17 May 2023

Linked audiences relate to strategies where publisher and advertiser audiences can be directly linked using an identifier at a 1:1 level 

What are Linked audiences?

Linked audiences rely on solutions that aim to enable cross-site tracking based on identifiable information that users have opted in to provide. They are often called universal or unified ID solutions. They work similarly to third-party cookies and replicate much of their current functionality. Some examples include Unified ID 2.0, ID5, Lotame Panorama ID and LiveRamp’s Ramp ID.

Linked ID systems typically fall into one of two categories: probabilistic or deterministic.

  • Deterministic IDs rely on persistent user signals such as an email address or phone number to create a user identifier in an authenticated state
  • Probabilistic identifiers use individual data points from disparate sources such as device and browser usage hashed IP and geolocation to create a user identifier in an anonymous, unauthenticated state
  • Some solutions will use one approach or another, and occasionally a mix of two approaches (probabilistic in an unauthenticated state migrating a user to a deterministic identifier after authentication)

In the case of UnifiedID 2.0, email addresses are secured using Privacy Enchancing Techniques (PETs) and passed back to the publisher as an anonymised token that can be shared with SSPs and stored on the user’s browser as a first-party cookie. With an increasing adoption from publishers’ tokenisation of log in data, a deterministic identity can be developed across environments and channels.  

A relatively new entrant into the identifier space is the joint venture between European telecoms Deutsche Telekom AG Orange SA, Telefónica S.A. and Vodafone Group plc - dubbed TrustPid. It aims to provide brands and publishers in France, Germany, Spain, Italy and the UK with a platform for their digital marketing and advertising activities via a tokenised user’s network subscription. The proposed tracking is limited per advertiser, with additional privacy measures through expiry of identifiers and limited enrichment of data.


Linked solutions are highly addressable and often allow advertisers to get a granular picture of their audience on a 1:1 level. Many proposed solutions are also interoperable, so will work across different environments.

However, there are challenges. There is a growing trend to limit the availability of datapoints available for the creation of identifiers such as email and IP address (Apple’s iCloud Relay/Hide My Email/Single Sign On services, Google’s Privacy Sandbox Gnatcatcher etc.) which may limit the overall effectiveness of certain approaches. Google has stated email addresses or other persistent identifiers will not be available as tracking solutions within its ecosystem, which may present difficulties in using linked solutions on Chrome and Android devices. However, as these IDs can operate in environments that were typically problematic for cookies (such as CTV), adoption further increases the scope of targeting and measurement in those contexts.

Another factor to consider is that the ICO has said it “will not accept proposals based on underlying ad tech concepts that replicate or seek to maintain the status quo.” This could potentially apply to solutions in this space, but it is not yet clear. You can find more on what the ICO has said here


  • Linked audiences describes environments where publisher and advertiser audiences can be linked using a token mapped through identity resolution and data management platforms
  • This type of approach commonly makes use of user-provided information (such as email address, name, address), provided at the point of sign-up for accounts with the relevant publisher
  • Use of specifically provided data from users can result in high data accuracy. However, it can also result in limited reach as these solutions generally require active participation from authenticated users only
  • IAB Tech Lab support for solutions in this area include: User ID 2.0, User-Enabled ID Tokens, IAB Tech Lab Tokenization Framework and Privacy Enhancing Techniques
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