Definition: 304 Not Modified

A “304 Not Modified” is a HTTP response status code indicating that a requested resource has not changed since the last time it was requested. The server sends this response code in response to a conditional GET request, which includes a “If-Modified-Since” or “If-None-Match” header. If the resource has not been modified, the server responds with a 304 status code and an empty body, rather than sending the entire resource again. This helps to improve performance by allowing the client to use a previously cached version of the resource, reducing the amount of data transfer and network usage.