Persistent Identifier
A persistent identifier is a stable value that recognizes the same user or device across sessions over time, such as a logged-in account ID or a first-party identifier. It enables continuity in personalization and measurement without relying on third-party cookies.
Persistent first-party identifiers, especially authenticated logins, are increasingly the durable backbone of recognition as third-party cookies and device IDs fade.
The most reliable persistent identifier is one the customer knowingly provides, like an account, which is both more durable and more privacy-respecting than passive tracking.
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