Definition
Unified ID 2.0 (UID2) is an open-source identity framework designed to enable privacy-conscious, addressable advertising without relying on third-party cookies. It uses hashed and encrypted email addresses (or other authenticated identifiers) as the foundation for a shared, interoperable identity layer across the digital advertising ecosystem.
In marketing, UID2 provides a mechanism for identifying and reaching audiences across channels while maintaining user consent and transparency. It is intended to support targeting, measurement, and personalization in environments where traditional cookie-based tracking is no longer viable.
How it relates to marketing
UID2 plays a role in replacing third-party cookies for audience targeting, frequency capping, attribution, and cross-channel measurement. It allows marketers, publishers, and ad tech platforms to operate on a shared identity framework built on authenticated user relationships rather than anonymous tracking.
It is particularly relevant in:
- Programmatic advertising
- Connected TV (CTV) and streaming environments
- Data clean rooms and privacy-safe data collaboration
- First-party data activation strategies
How to calculate Unified ID 2.0
UID2 itself is not a metric and therefore is not calculated in the traditional sense. However, the creation process involves:
- Collecting a user’s email address (with consent)
- Normalizing and hashing the email
- Encrypting the hashed value into a UID2 token
- Refreshing and rotating tokens periodically for security
The “value” of UID2 within a marketing context is typically assessed through downstream performance metrics such as match rates, addressability, and campaign effectiveness.
How to utilize Unified ID 2.0
Organizations use UID2 to enable identity resolution and activation in a privacy-centric environment.
Common use cases include:
- Audience targeting: Matching authenticated users across participating platforms
- Frequency management: Controlling ad exposure across devices and channels
- Measurement and attribution: Linking ad exposure to outcomes without cookies
- Data collaboration: Enabling secure data sharing between brands and publishers
- CTV advertising: Supporting identity in environments where cookies are not available
Implementation typically requires:
- Integration with identity providers or UID2 operators
- Collection of consented first-party data
- Alignment with participating SSPs, DSPs, and publishers
Comparison to similar approaches
| Approach | Identifier Type | Dependency | Privacy Model | Interoperability | Common Use Case |
|---|---|---|---|---|---|
| UID2 | Hashed email (authenticated) | First-party data | Consent-driven, encrypted tokens | High (open-source ecosystem) | Programmatic, CTV |
| Third-party cookies | Browser-based ID | Browser | Implicit tracking | Moderate (browser-limited) | Web retargeting |
| IDFA/GAID | Device IDs | Mobile OS | User opt-in (declining availability) | Low to moderate | Mobile app advertising |
| Publisher first-party IDs | Site-specific login | Publisher | Consent-based | Low (walled garden) | On-site personalization |
| Clean room IDs | Pseudonymized datasets | Data partnerships | Strict governance | Moderate | Data collaboration, measurement |
Best practices
- Prioritize transparent consent collection and clear value exchange with users
- Strengthen first-party data strategies to support identity frameworks like UID2
- Integrate UID2 alongside other identity solutions rather than relying on a single approach
- Regularly audit data governance and compliance practices
- Align marketing, legal, and IT teams to manage implementation and risk
- Monitor match rates and performance to evaluate effectiveness
- Use UID2 in conjunction with contextual targeting and modeled approaches
Future trends
- Increased adoption in CTV and streaming ecosystems
- Greater integration with data clean rooms and privacy-enhancing technologies
- Expansion of interoperable identity frameworks beyond email-based identifiers
- Continued regulatory influence shaping consent and data usage requirements
- Hybrid identity strategies combining deterministic (UID2) and probabilistic methods
- Evolution toward decentralized identity and user-controlled data models
Related Terms
- Identity Resolution
- First-Party Data
- Data Clean Room
- Addressable Advertising
- Cookie Deprecation
- Hashed Identifiers
- Consent Management Platform (CMP)
- Programmatic Advertising
- Customer Data Platform (CDP)
- Privacy-Enhancing Technologies (PETs)