Glossary / Networking & connectivity

HTTP status codes (404, 500…)

Status codes are the three-digit verdict a server returns with every response: 2xx means success, 3xx redirection, 4xx a client-side problem (404 not found, 403 forbidden), 5xx a server-side failure (500 crash, 503 overloaded). They matter beyond debugging — search engines act on them, so a page that answers 200 instead of 404, or redirects with 302 instead of 301, quietly damages SEO.