HTTP Status Codes

This is used for caching purposes. It is telling to client that response has not been modified. So, client can continue to use same cached version of response. A conditional GET or HEAD request has been received and would have resulted in a 200 OK response if it were not for the fact that the condition evaluated to false. If the client has performed a conditional GET request and access is allowed, but the document has not been modified, the server SHOULD respond with this status code. The 304 response MUST NOT contain a message-body, and thus is always terminated by the first empty line after the header fields. The response MUST include the following header fields: If a clockless origin server obeys these rules, and proxies and clients add their own Date to any response received without one, caches will operate correctly. ETag and/or Content-Location, if the header would have been sent in a 200 response to the same request Expires, Cache-Control, and/or Vary, if t...

The request has more than one possible responses. User-agent or user should choose one of them. There is no standardized way to choose one of the responses. The target resource has more than one representation, each with its own more specific identifier, and information about the alternatives is being provided so that the user (or user agent) can select a preferred representation by redirecting its request to one or more of those identifiers. In other words, the server desires that the user agent engage in reactive negotiation to select the most appropriate representation(s) for its needs. If the server has a preferred choice, the server SHOULD generate a Location header field containing a preferred choice's URI reference. The user agent MAY use the Location field value for automatic redirection. For request methods other than HEAD, the server SHOULD generate a payload in the 300 response containing a list of representation metadata and URI reference(s) from w...