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Status Code 304 – The is status code used for browser caching. If the response has not been modified, the client/user can continue to use the same response/cached version. For example, a browser can request if a resource has been modified since a specific time. If it hasn’t, the status code 304 is sent. If it has been modified, a status code 200 is sent, along with the resource.
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A 304 "Not Modified message" is an HTTP response status code indicating that the requested resource has not been modified since the previous transmission, so there is no need to retransmit the requested resource to the client.