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Third‑Party Cookies
Tracking
Cookies scoped to a third-party domain used for cross-site identifier reuse.
Definition
Third-party cookies are stored under a third-party domain and sent when that third-party resource loads across many first-party sites, enabling cross-site identity linking.
In plain English
Cookies scoped to a third-party domain used for cross-site identifier reuse.
Why this matters
Why it matters: They are a major mechanism for cross-site tracking and profiling.
Example
Example: Embedded ad iframe reads its cookie to link impressions across publishers.