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Data collaboration depends on identifiers—the keys that connect records across different organizations and systems. When two companies want to find overlapping customers or match behavioral data to a customer file, identifiers make that connection possible. But identifiers in data collaboration come with unique challenges: privacy regulations require protection of personal information, different organizations use different identifier systems, and the fragmented digital landscape means a single person might be represented by dozens of different identifiers across devices and channels.

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Why identifiers matter

Consider a retail company that wants to target its existing customers with digital advertising. They have email addresses from their CRM, but ad platforms work with mobile device IDs and cookies. Without identifier mapping, their customer data is siloed and unusable for digital activation. Data collaboration platforms solve this by:
  • Pseudonymizing identifiers (hashing emails) so they can be matched without exposing PII
  • Mapping between identifier types (connecting hashed emails to mobile ad IDs)
  • Standardizing identifier formats so data from different sources can be matched

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The identifier ecosystem

The digital advertising and data collaboration ecosystem uses several categories of identifiers:
CategoryExamplesPersistencePrivacy Status
Device IDsIDFA (iOS), GAID (Android)Resettable by userPseudo-anonymous
Browser IDsThird-party cookies, first-party cookiesSession or persistentPseudo-anonymous
Hashed PIIMD5/SHA-256 hashed emails and phonesPermanentPseudonymized
Universal IDsUID2, RampID, ID5VariesPseudonymized
Each identifier type serves different use cases and has different trade-offs in terms of reach, accuracy, and privacy.

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Identifier challenges

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Cross-device identity

A single consumer might use a smartphone, tablet, laptop, and smart TV—each with different identifiers. Connecting these identifiers to understand that they represent the same person is a core challenge in data collaboration. Privacy regulations (GDPR, CCPA) and platform policies (Apple’s ATT, Google’s Privacy Sandbox) increasingly restrict how identifiers can be collected and used. Organizations must balance data utility with privacy compliance.

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Identifier deprecation

The digital ecosystem is in flux. Third-party cookies are being phased out, mobile ad ID availability is declining, and new privacy-preserving identifiers are emerging. Data strategies must adapt to this changing landscape.

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Related content

Identifier Types

Categories of identifiers used in data collaboration

Mobile Ad IDs

Understanding IDFA, GAID, and mobile device identifiers

ID Mapping

Connecting identifiers across devices and channels

UID2

The Unified ID 2.0 privacy-preserving identifier

Data Onboarding

Translating offline data for digital activation

Data Pseudonymization

How hashing protects identifiers