HTTP Status Code
The server response code that tells browsers and crawlers whether a URL loaded, redirected, moved, or failed.
HTTP status codes are crawl signals. A 200 means the page loaded successfully, 301 and 302 indicate redirects, 404 means not found, and 5xx errors mean the server failed.
SEOs use status codes during migrations, audits, and crawl diagnostics to find broken URLs, redirect mistakes, soft errors, and pages that search engines cannot access reliably.