200 - OK; Standard response for successful HTTP requests.
201 - Created; Request has been fulfilled. New resource created.
204 - No Content; Request processed. No content returned.
301 - Moved Permanently; This and all future requests directed to the given URI.
304 - Not Modified; Resource has not been modified since last requested.
400 - Bad Request; Request cannot be fulfilled due to bad syntax.
401 - Unauthorized; Authentication is possible, but has failed.
403 - Forbidden; Server refuses to respond to request.
404 - Not Found; Requested resource could not be found.
500 - Internal Server Error; Generic error message when server fails.
501 - Not Implemented; Server does not recognize method or lacks ability to fulfill.
503 - Service Unavailable; Server is currently unavailable.