HTTP response status codes tell the client the result of the requested action (GET, POST, etc.). Some common codes you’ll see in HTTP responses are:
200 OK : The request succeeded.
201 Created : The request succeeded and a resource was created.
400 Bad Request : The request was not fulfilled due to an error in the request, such as a typo or missing data.
401 Unauthorized : The request was not fulfilled because the client is not authenticated or authorized to access the requested resource.
403 Forbidden : The request was not fulfilled because the client is authenticated, but not authorized to access the requested resource.
404 Not Found : The request was not fulfilled because the server could not locate the requested resource.
500 Internal Server Error : The request was not fulfilled due to an unexpected problem with the server. (See also: 500 Internal Server Errors: What They Are & How to Fix Them)
502 Bad Gateway : The request was not fulfilled due to an invalid response from an upstream server.
503 Service Unavailable : The server was unable to process the request due to maintenance, overloading, or another temporary interference.
