Identity Resolution
AnalyticsAlso: ID Resolution · Customer Identity Resolution · Cross-Device Identity
Quick definition
The process of connecting multiple data points — browsing sessions, devices, email addresses, purchase records — to build a unified profile of an individual customer across touchpoints.
Where it shows up in the data
Deterministic matching links identities using known identifiers like email addresses — certain and privacy-compliant when users have consented. Probabilistic matching infers identity from device fingerprinting and behavioural signals — less accurate and increasingly restricted by privacy regulations.
A database that stores all known identifiers for each customer: email addresses, phone numbers, CRM IDs, cookie IDs and device IDs. When a user logs in or provides their email, all their previous anonymous activity can be linked to that profile.
Browsers are phasing out third-party cookies, which historically enabled cross-site tracking. Identity resolution based on first-party data (users who have logged in or submitted a form) is the privacy-safe replacement.
CDPs are the technology layer that manages identity resolution at scale, ingesting data from multiple sources, resolving identities and making unified profiles available for marketing activation.
What it actually means
Every time a visitor interacts with your website, they generate data. But the same person might visit on a laptop, then a phone, then click an email link — leaving three separate data trails that analytics treats as three different users. Identity resolution is the process of connecting those trails to understand that it was one person at three points in their journey. This matters for accurate attribution, personalised messaging and building retargeting audiences that do not decay as cookies expire.
Without identity resolution, you are marketing to sessions and devices, not to people.
How it shows up
In GA4, User-ID reporting shows how many known users you have versus anonymous users, and allows cross-device session joining. A high User-ID match rate (above 30% of sessions having a known user) suggests strong first-party identity coverage.
The Australian context
Under the Australian Privacy Act 1988 and its upcoming amendments, identity resolution activities require clear disclosure and consent. Hashing email addresses for matching purposes is generally permitted but must be covered in your privacy policy. CDPs operating in Australia must comply with the Privacy Act's cross-border data transfer provisions.
Where people get this wrong
Related terms
Common questions
What is a Customer Data Platform (CDP)?
A CDP is software that collects customer data from multiple sources (website, CRM, email, ads) and creates unified customer profiles through identity resolution. It is the technical layer that enables personalisation and consistent cross-channel attribution.
How does Google Analytics handle identity resolution?
GA4 supports User-ID tracking — when you pass a hashed user identifier (from a login event or email capture), GA4 can join sessions across devices for that user. This requires implementation via Google Tag Manager or direct gtag configuration.
Is identity resolution legal in Australia?
Yes, with proper consent. Collecting emails with clear privacy consent, hashing them for ad platform matching (Meta's Custom Audiences, Google Customer Match) and GA4 User-ID implementation are all compliant when disclosed in your privacy policy and covered by user consent.
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About New Rebellion
New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.
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