Audience segments a publisher builds from its own registered users and on-site behavior and offers to buyers directly or through the IAB Tech Lab's Seller Defined Audiences specification. Publisher data is one of the main proposed replacements for third-party cookie segments on the open web.
Cite this entry:
Agency Echelon. "Publisher First-Party Data." Agency Echelon Reference, reviewed September 2026. https://agencyechelon.com/reference/glossary/publisher-first-party-data/