The most common HTTP response codes are:
- 200 OK – The server successfully processed the request
- 404 Not Found – The requested resource could not be found
- 500 Internal Server Error – An unexpected condition was encountered by the server
- 400 Bad Request – The request could not be understood or was missing required parameters
- 401 Unauthorized – Authentication failed or user does not have permissions for the requested operation
- 403 Forbidden – Access to the requested resource is forbidden
- 503 Service Unavailable – The server is currently unavailable (due to maintenance or overload) and unable to handle the request.
