Etag HTTP Header

• Etag (also known as entity tag) is a unique identifier for a resource
• This is used to cache the resources that are unchanged
• When a request is recieved by server, it generates response and attaches Etag
• In the subsequent request, application requests for the same resource with If-None-Match header with the value of Etag received in previous step
• Server compares the value of If-None-match header with Etag identifier value on server
• If the values match server responds with 304(Not modified) status code with the empty body
• Application can use the cached response