Glossary: System Design Basics in PHP

HTTP status codes

Also written: Status code, HTTP status code, status codes, 200, 201, 301, 302, 400, 401, 403, 404, 409, 429, 500, 503, Moved Permanently, Found

The number that starts an HTTP response: 2xx means success, 4xx the client's mistake, 5xx a server problem. Common codes: 200 OK, 201 Created, 301 moved for good, 302 moved for now, 400 bad request, 401 not logged in (caller not proven), 403 not allowed (caller known), 404 not found, 409 conflict with current state, 429 too many requests, 500 server error, 503 service unavailable.