The plain-English version
An HTTP validator identifying a particular representation version for conditional requests.
Why it matters
It can support efficient revalidation or detect that an update was based on an outdated representation.
Let’s make it click
A client sends a previously received validator and the server decides whether the representation changed.
Vibe Bro’s heads-up
An ETag is not automatically a record permission check or a universal content hash with a guaranteed format.
The docs behind it
Documentation links checked .
Editorial review · October 28, 2026
Supported: MDN documents validators, conditional requests, and edit-conflict checks. The entry correctly avoids treating an ETag as authorization or a guaranteed content hash.