Data & identity · also called ID graph, identity resolution
Identity graph
An identity graph is a database that links the many identifiers belonging to the same person or household, such as emails, device IDs, cookies and IP addresses, into one profile.
One person might appear to advertisers as a work laptop cookie, a phone's advertising ID, a smart TV, a hashed email and a loyalty-card number. An identity graph connects those dots, saying these identifiers probably or definitely belong to the same person or household.
Graphs are built from two kinds of evidence. Deterministic links come from definite signals, such as logging in with the same email on two devices. Probabilistic links are statistical guesses based on shared IP addresses, locations, behaviour patterns and device traits. Most commercial graphs, from companies such as LiveRamp, Experian and TransUnion, and from walled gardens, combine both.
Identity graphs enable cross-device targeting, reach and frequency management, measurement and household targeting on Addressable TV. They are also a privacy hot spot: combining identifiers can re-identify supposedly anonymous data, and laws like GDPR and CCPA / CPRA regulate how graphs are built and used. Accuracy varies, especially for probabilistic links, so buyers should ask how links were made.
Think of it like this
An identity graph is like a family tree, except instead of relatives it connects all the different nametags one person wears online.
An example
An identity provider links a hashed email seen on a US retailer's site to two mobile ad IDs and a CTV household ID, letting an advertiser cap frequency at five exposures across all four screens.
Related terms
Deterministic matching
Deterministic matching links identifiers to the same person using definite, shared information, such as the same login email or phone number, rather than statistical inference.
Probabilistic matching
Probabilistic matching links devices or identifiers to the same person or household using statistical inference from signals like shared IP address, location, timing and device traits, with some uncertainty.
Hashed email
A hashed email is an email address transformed by a one-way cryptographic function, usually SHA-256, into a fixed string used to match users across systems without sharing the plain address.
Household ID
A household ID is an identifier representing a home and the devices in it, rather than one person, used mainly in CTV and addressable TV for targeting, frequency capping and measurement.
RampID
RampID is LiveRamp's pseudonymous, people-based identifier, which links a person's or household's online and offline identifiers so advertisers and publishers can match audiences without sharing raw personal data.
Sources: GDPR Article 4: definitions, California Attorney General: CCPA