Page Comparison

The 1xx (Informational) class of status code indicates an interim
   response for communicating connection status or request progress
   prior to completing the requested action and sending a final
   response.

The 2xx (Successful) class of status code indicates that the client's
   request was successfully received, understood, and accepted.

 The 300 (Multiple Choices) status code indicates that 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 ().

The 301 (Moved Permanently) status code indicates that the target
   resource has been assigned a new permanent URI and any future
   references to this resource ought to use one of the enclosed URIs.
   Clients with link-editing capabilities ought to automatically re-link
   references to the effective request URI to one or more of the new
   references sent by the server, where possible.

The 302 (Found) status code indicates that the target resource
   resides temporarily under a different URI.  Since the redirection
   might be altered on occasion, the client ought to continue to use the
   effective request URI for future requests.

The 303 (See Other) status code indicates that the server is
   redirecting the user agent to a different resource, as indicated by a
   URI in the Location header field, which is intended to provide an
   indirect response to the original request.  A user agent can perform
   a retrieval request targeting that URI (a GET or HEAD request if
   using HTTP), which might also be redirected, and present the eventual
   result as an answer to the original request.  Note that the new URI
   in the Location header field is not considered equivalent to the
   effective request URI.

The 305 (Use Proxy) status code was defined in a previous version of
   this specification and is now deprecated (Appendix B).

The 306 status code was defined in a previous version of this
   specification, is no longer used, and the code is reserved.

The 307 (Temporary Redirect) status code indicates that the target
   resource resides temporarily under a different URI and the user agent
   MUST NOT change the request method if it performs an automatic
   redirection to that URI.  Since the redirection can change over time,
   the client ought to continue using the original effective request URI
   for future requests.

The 400 (Bad Request) status code indicates that the server cannot or
   will not process the request due to something that is perceived to be
   a client error (e.g., malformed request syntax, invalid request
   message framing, or deceptive request routing).

The 403 (Forbidden) status code indicates that the server understood
   the request but refuses to authorize it.  A server that wishes to
   make public why the request has been forbidden can describe that
   reason in the response payload (if any).

The 404 (Not Found) status code indicates that the origin server did
   not find a current representation for the target resource or is not
   willing to disclose that one exists.  A 404 status code does not
   indicate whether this lack of representation is temporary or
   permanent; the 410 (Gone) status code is preferred over 404 if the
   origin server knows, presumably through some configurable means, that
   the condition is likely to be permanent.

The 405 (Method Not Allowed) status code indicates that the method
   received in the request-line is known by the origin server but not
   supported by the target resource.  The origin server MUST generate an
   Allow header field in a 405 response containing a list of the target
   resource's currently supported methods.

The 406 (Not Acceptable) status code indicates that the target
   resource does not have a current representation that would be
   acceptable to the user agent, according to the proactive negotiation
   header fields received in the request (), and the server
   is unwilling to supply a default representation.

The 408 (Request Timeout) status code indicates that the server did
   not receive a complete request message within the time that it was
   prepared to wait.  A server SHOULD send the "close" connection option
   () in the response, since 408 implies that
   the server has decided to close the connection rather than continue
   waiting.  If the client has an outstanding request in transit, the
   client MAY repeat that request on a new connection.

The 409 (Conflict) status code indicates that the request could not
   be completed due to a conflict with the current state of the target
   resource.  This code is used in situations where the user might be
   able to resolve the conflict and resubmit the request.  The server
   SHOULD generate a payload that includes enough information for a user
   to recognize the source of the conflict.

The 410 (Gone) status code indicates that access to the target
   resource is no longer available at the origin server and that this
   condition is likely to be permanent.  If the origin server does not 
   know, or has no facility to determine, whether or not the condition
   is permanent, the status code 404 (Not Found) ought to be used
   instead.

The 411 (Length Required) status code indicates that the server
   refuses to accept the request without a defined Content-Length
   ().  The client MAY repeat the request if
   it adds a valid Content-Length header field containing the length of
   the message body in the request message.

The 413 (Payload Too Large) status code indicates that the server is
   refusing to process a request because the request payload is larger
   than the server is willing or able to process.  The server MAY close
   the connection to prevent the client from continuing the request.

   The 414 (URI Too Long) status code indicates that the server is
   refusing to service the request because the request-target (
   ) is longer than the server is willing to interpret.

The 415 (Unsupported Media Type) status code indicates that the
   origin server is refusing to service the request because the payload
   is in a format not supported by this method on the target resource.
   The format problem might be due to the request's indicated
   Content-Type or Content-Encoding, or as a result of inspecting the
   data directly.

The 417 (Expectation Failed) status code indicates that the
   expectation given in the request's Expect header field
   () could not be met by at least one of the inbound
   servers.

The 426 (Upgrade Required) status code indicates that the server
   refuses to perform the request using the current protocol but might
   be willing to do so after the client upgrades to a different
   protocol.  The server MUST send an Upgrade header field in a 426
   response to indicate the required protocol(s) ().

The 500 (Internal Server Error) status code indicates that the server
   encountered an unexpected condition that prevented it from fulfilling
   the request.

The 501 (Not Implemented) status code indicates that the server does
   not support the functionality required to fulfill the request.  This
   is the appropriate response when the server does not recognize the
   request method and is not capable of supporting it for any resource.

The 502 (Bad Gateway) status code indicates that the server, while
   acting as a gateway or proxy, received an invalid response from an
   inbound server it accessed while attempting to fulfill the request.

The 503 (Service Unavailable) status code indicates that the server
   is currently unable to handle the request due to a temporary overload
   or scheduled maintenance, which will likely be alleviated after some
   delay.  The server MAY send a Retry-After header field
   () to suggest an appropriate amount of time for the
   client to wait before retrying the request.

      Note: The existence of the 503 status code does not imply that a
      server has to use it when becoming overloaded.  Some servers might
      simply refuse the connection.

The 504 (Gateway Timeout) status code indicates that the server,
   while acting as a gateway or proxy, did not receive a timely response
   from an upstream server it needed to access in order to complete the
   request.

The 505 (HTTP Version Not Supported) status code indicates that the
   server does not support, or refuses to support, the major version of
   HTTP that was used in the request message.  The server is indicating
   that it is unable or unwilling to complete the request using the same
   major version as the client, as described in , other than with this error message.  The server SHOULD
   generate a representation for the 505 response that describes why
   that version is not supported and what other protocols are supported
   by that server.