HTTP(s) response status codes indicate whether a specific HTTP(s) request has been successfully completed. There are five classes defined by the standard:
1xx informational response – the request was received, continuing process;
2xx successful – the request was successfully received, understood, and accepted; All pages that will be indexed must return a 200 OK code.
3xx redirection – further action needs to be taken in order to complete the request;
4xx client error – the request contains bad syntax or cannot be fulfilled;
5xx server error – the server failed to fulfil an apparently valid request.
HTTP(s) response status codes indicate whether a specific HTTP(s) request has been successfully completed.