Table of Contents
About
The HTTP ETag (entity tag) response header is an identifier for a specific version of a resource1. It lets caches be more efficient and save bandwidth, as a web server does not need to resend a full response if the content has not changed. Additionally, ETags help to prevent simultaneous updates of a resource from overwriting each other (“mid-air collisions”).
If the resource at a given URL changes, a new Etag value must be generated. A comparison of them can determine whether two representations of a resource are the same.
Characteristics
See Forbidden request header, HTTP Response headers, Representation headers
| Header type | Response header, Representation header |
|---|---|
| Forbidden request header | No |
Anki
Links
References
MDN. “ETag”. Available at: https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/ETag. (Accessed: ). ↩︎