HTTP status codes are standardised three-digit numbers included in every HTTP response. They tell the client (browser or application) whether the request succeeded, requires further action, or failed — and why.
Status Code Classes
- 1xx — Informational: Request received, processing continues. E.g.
100 Continue. - 2xx — Success: Request was received, understood and accepted. E.g.
200 OK,201 Created. - 3xx — Redirection: Further action needed to complete the request. E.g.
301 Moved Permanently,302 Found. - 4xx — Client Errors: The request contains bad syntax or cannot be fulfilled. E.g.
400 Bad Request,401 Unauthorized,403 Forbidden,404 Not Found. - 5xx — Server Errors: The server failed to fulfil a valid request. E.g.
500 Internal Server Error,503 Service Unavailable.
Most Important for SEO
- 200 — Page loads correctly. Google indexes it.
- 301 — Permanent redirect. Passes link equity.
- 404 — Page not found. Remove from sitemap.
- 500 — Server error. Googlebot may temporarily stop crawling.