— Indicates the "where" (different domain).
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:
If you are looking for the exact syntax used in a network request, it usually looks like this: sec,fetch,site:,cross,site
— Indicates the "what" (data fetch, not an image or script).
: The request started from a related subdomain. The "Post" Connection — Indicates the "where" (different domain)
: 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
: This is the most critical header in your list. It tells the server the relationship between the request initiator's origin and the target resource's origin. : The request started from a related subdomain
This looks like you're piecing together the technical components of , specifically those used for Cross-Origin Resource Sharing (CORS) and Cross-Site Request Forgery (CSRF) protection. The Concept: Fetch Metadata ( sec-fetch-* )