Http statuses
From wikinotes
HTTP responses include a 3x digit status-code.
Responses are standardized within 5x 100-number ranges.
Documentation
IANA spec https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml wikipedia https://en.wikipedia.org/wiki/List_of_HTTP_status_codes
Overview
1xx # information 2xx # success 3xx # redirect 4xx # client error 5xx # server error