Identity resolution
Identity resolution is the process of recognising that different identifiers (an email address, a phone, a cookie, a TV) belong to the same person or household.
The same person leaves traces under different identifiers: the email they shop with, their phone’s advertising ID, the cookie on their work laptop, the IP address of the TV in the living room. Identity resolution links them in an identity graph. It can be deterministic, when it relies on a reliable shared data point (the same person logs in on two devices), or probabilistic, when it infers the link from signals such as the wifi network or usage patterns, with less certainty and more reach.
Cross-device targeting, frequency control across screens and measurement that follows the person rather than the device all depend on it. With the decline of third-party cookies, identifiers based on hashed emails, such as UID2 or RampID, have gained ground, as have the large platforms’ own graphs. Because it processes personal data, it needs a legal basis and consent under the GDPR.
