First-Party vs Third-Party Cookies
First-party cookies are set by the website a user is visiting, while third-party cookies are set by other domains such as ad or tracking networks; browsers increasingly block third-party cookies, pushing affiliate tracking toward first-party and server-side methods.
A first-party cookie belongs to the domain in the address bar and is generally trusted and persistent. A third-party cookie is set by a different domain embedded in the page — historically how cross-site ad and affiliate tracking worked.
Because Safari, Firefox, and Chrome now restrict or block third-party cookies, affiliate programs increasingly rely on first-party cookies set by the merchant plus server-to-server tracking, which do not depend on cross-site cookies and keep attribution accurate as the cookie landscape tightens.
See also
- Cookie Window
A cookie window (or cookie duration) is the length of time after a referral click during which a resulting conversion will still be credited to that affiliate.
- S2S / Postback Tracking
Server-to-server (S2S) postback tracking records conversions by sending an event directly from the merchant's backend to the affiliate platform, without relying on browser cookies.
- Attribution
Attribution is the process of determining which affiliate or marketing touchpoint should receive credit — and the commission — for a conversion.
- Incrementality
Incrementality measures how many conversions a marketing channel or partner truly caused that would not have happened otherwise, separating genuinely driven sales from those that would have occurred anyway.
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