Reference / Glossary / Infrastructure and standards
First-Party Cookie
A cookie set by the domain the user is visiting, used for logins, preferences, analytics, and, since third-party cookies declined, for advertising measurement through first-party-domain tagging. Browsers restrict script-set first-party cookies less than third-party ones but still limit their lifespan.
Cite this entry:
Agency Echelon. "First-Party Cookie." Agency Echelon Reference, reviewed September 2026. https://agencyechelon.com/reference/glossary/first-party-cookie/