1. 2xx request succeeded
2. 3xx redirects
3. Errors in 4xx clients
403 Forbidden - access is not required even with authorization
404 The server did not find the specified resource, the document does not exist
4. Errors in 5xx servers
500 Internal Server Error - The server could not complete the request due to an unexpected condition
5. 1xx request issued
100 The web server has received the request correctly
200 OK, request completed
201 Normal, followed by the POST command
202 OK, accepted for processing, but processing has not yet completed
203 OK, partial information - the returned information is only partial
204 OK, no response - the request was received, but there is no information to send back
301 Moved - the requested data has a new location and the change is permanent
302 Found - The requested data temporarily has a different URI
303 The response to the request can be found under another URI and should be retrieved using the GET method
304 Not Modified - The document was not modified as expected
305 Using Proxy - The requested resource must be accessed through the proxy provided in the location field
306 Not used - no longer used, keep this code for future use
400 Bad Request - The request has a syntax problem, or the request cannot be satisfied
401 Unauthorized - Client not authorized to access data
402 Payment Required - Indicates that the billing system is active
403 Forbidden - access is not required even with authorization
404 Not Found - The server cannot find the given resource, the document does not exist
407 Proxy Authentication Request - The client must first authenticate itself with the proxy
500 Internal Error - The server could not complete the request due to an unexpected condition
501 Not Executed - The requested tool is not supported by the server
502 Bad Gateway - The server received an invalid response from the upstream server
503 Unavailable - The server was unable to process the request due to temporary overload or maintenance