Identity

Third-Party Cookie — Definition & Explanation

A cookie set by a domain other than the one the user is visiting, used for cross-site tracking, retargeting, and audience-based advertising. Major browsers are deprecating third-party cookies, fundamentally reshaping digital advertising targeting.

How Third-Party Cookie Works

Third-party cookies are set by ad tech platforms (SSPs, DSPs, measurement vendors) when their pixels fire on publisher pages. They enable the same platform to recognize users across different websites for targeting and attribution.

Why Third-Party Cookie Matters for Publishers

Third-party cookie deprecation is reshaping publisher monetization strategies. Publishers investing in first-party data, identity frameworks, and contextual targeting will be better positioned for the cookieless future.

Frequently Asked Questions

When will third-party cookies be fully deprecated?

Google Chrome's timeline has shifted multiple times. Safari and Firefox already block third-party cookies by default. Publishers should plan for a cookieless environment now.

How does cookie deprecation affect publisher CPMs?

Publishers heavily reliant on third-party cookie-based targeting may see 20-40% CPM declines. First-party data strategies and identity solutions mitigate this impact.

How is Stellor Media preparing for cookie deprecation?

Stellor supports UID2, RampID, contextual targeting enrichment, and first-party data activation to maintain publisher revenue in cookie-restricted environments.

Related Terms

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