Sec,fetch,site:,cross,site -

— Indicates the "how" (using the Fetch API/CORS).

— Indicates the "where" (different domain).

If you are looking for the exact syntax used in a network request, it usually looks like this: sec,fetch,site:,cross,site

When you send a request (like submitting a login form or updating account settings), the browser automatically attaches these headers. A secure server will check them to prevent attacks:

: The browser adds sec-fetch-site: cross-site and sec-fetch-mode: navigate (or cors ). — Indicates the "how" (using the Fetch API/CORS)

: A user on site-a.com clicks a button that sends a POST to site-b.com .

: The server sees cross-site on a sensitive POST action and rejects it because it knows this request didn't originate from its own trusted frontend. Summary of the Headers A secure server will check them to prevent

: This indicates the request originated from a completely different website (e.g., attacker.com trying to fetch data from yourbank.com ). Value: same-origin : The request started on your own site.