Useful HTTP status:

200 OK
201 Created
204 No Content
205 Reset Content
206 Partial Content
400 Bad Request
401 Unauthorized
404 Not Found
405 Method Not Allowed
403 Forbidden
406 Not Acceptable
407 Proxy Authentication Required
408 Request Timeout
411 Length Required
413 Requested Entity Too Large
414 Requested URL Too Long
415 Unsupported Media Type
500 Internal Server Error
502 Bad Gateway
501Not Implemented
503 Service Unavailable
504 Gateway Timeout
505 HTTP Version Not Supported