Standard HTTP Status Codes

The official registry of HTTP response status codes are maintained by Internet Assigned Numbers Authority (IANA).

You can find a general description of the codes at https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
The following are the most commonly used response codes:
Error Code Description
200 OK
201 Created
202 Accepted
204 No Content
301 Moved Permanently
303 See Other
304 Not Modified
307 Temporary Redirect
400 Bad Request
401 Unauthorized
403 Forbidden
404 Not Found
406 Not Acceptable
409 Conflict
410 Gone
412 Precondition Failed
415 Unsupported Media Type
500 Internal Server Error
503 Service Unavailable