{"json_modified": "2016-10-14T05:17:29.428353", "uuid": "98c1c733-ded7-42ad-b4a5-2965547e6adf", "title": "ETag", "url": "/en-US/docs/Web/HTTP/Headers/ETag", "tags": ["Response", "Reference", "header", "HTTP"], "translations": [], "modified": "2016-10-14T05:17:29", "label": "ETag", "localization_tags": [], "locale": "en-US", "id": 192827, "last_edit": "2016-08-31T04:25:31", "summary": "The <strong><code>ETag</code></strong> HTTP response header is an identifier for a specific version of a resource. It allows caches to be more efficient, and saves bandwidth, as a web server does not need to send a full response if the content has not changed. On the other side, if the content has changed, etags are useful to help prevent simultaneous updates of a resource from overwriting each other (\"mid-air collisions\").", "sections": [{"id": "Quick_Links", "title": null}, {"id": "Syntax", "title": "Syntax"}, {"id": "Directives", "title": "Directives"}, {"id": "Examples", "title": "Examples"}, {"id": "Avoiding_mid-air_collisions", "title": "Avoiding mid-air collisions"}, {"id": "Caching_of_unchanged_resources", "title": "Caching of unchanged resources"}, {"id": "Specifications", "title": "Specifications"}, {"id": "Browser_compatibility", "title": "Browser compatibility"}, {"id": "See_also", "title": "See also"}], "slug": "Web/HTTP/Headers/ETag", "review_tags": []}