HTTP response codes indicates whether a specific request has been successfully completed. They are grouped as five main categories, 


1xx - Informational 

2xx - Success 

3xx - Redirection 

301 - Moved permanently 

302 - Found 

304 - Not modified 

307 - Temporary Redirect 

308 - Permanent Redirect 

4xx - Client Error 

400 - Bad request 

401 - unauthorised 

402 - payment required 

403 - Forbidden 

404 - Not found 

405 - Method not allowed 

413 - Request entity too large 

5xx - server error 

500 - Internal server error 

502 - Bad gateway 

503 - service unavailable

504 - Gateway timeout