Audience segment
In practice, for a UK buyer
The paragraph above is the neutral answer. This is the part a vendor glossary leaves out.
The critical thing about a segment is that it is somebody's model of a group, not the group. 'IT decision makers' is a set of people a data vendor believes are IT decision makers, built from signals of varying quality. AdBuyMCP's design decision here is structural: the language model extracts semantics from your brief and never emits a vendor segment identifier. Deterministic registry tables do that, matching your terms against catalogue keywords by whole-token overlap. That is why a compiled plan can be audited line by line, and why a hallucinated segment cannot reach a buy.
Goes deeper: What one audience becomes on seven channels
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.
Third-party data
Audience data collected by one organisation and licensed to another for targeting, with no direct relationship between the licensee and the people described. Sold as segments through data marketplaces attached to buying platforms.
Fidelity score
A published score out of 100 answering one question: how much of an audience definition survives translation into a channel's native targeting words. It is a property of that translation rather than a forecast, and it is not a quality rating.
Contextual targeting
Targeting based on the content an advert appears beside rather than on data about the person seeing it — a show, a genre, a page subject, a venue type. Requires no personal data about the audience.
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