Unified ID 2.0 (UID2)
In practice, for a UK buyer
The paragraph above is the neutral answer. This is the part a vendor glossary leaves out.
Mentioned here mainly so the family is legible: UID2 is the North American implementation and EUID the European one, and a vendor discussing one may mean either. Neither is in use here today.
What this one connects to
Most confusion in media buying comes from two adjacent terms being used interchangeably, so these are the neighbours worth reading next.
European Unified ID (EUID)
A consent-based identifier for European advertising, derived from a hashed email or phone number provided with consent, designed to let first-party audiences be addressed across publishers without third-party cookies.
First-party data
Data an organisation has collected directly from its own customers and visitors — a CRM list, purchase history, site behaviour. Distinguished from third-party data by the existence of a direct relationship with the person it describes.
Identity resolution
The process of deciding that two different identifiers refer to the same person or household, so that behaviour seen under one can be joined to the other.
More on targeting and identity
How an audience is described to a seller, and how much of the description survives. Most of the honest difficulty in media buying lives here.
45 minutes. Bring a real brief and we compile it live. You describe one audience and watch it compile into seven targeting specifications, each with the score for how much of the definition survived.
Talk it through