304s
The 304s refer to a combination of a HTTP status code and a related HTTP request, specifically HTTP/1.0. When a web server receives an HTTP request, but finds no resource matching the request's URL, it returns a response indicating that the requested resource cannot be found. This is known as a 304 response from the server, in which the server returns an empty response body, but lists the headers that would be returned in a successful request.
In order to get a 304 response, a browser or client first sends a request for a
A 304 response includes some additional information: the Last-Modified and ETag headers. These headers are used