What is HTTP status codes?

HTTP status codes are the three-digit numbers a server returns with every response. They tell crawlers and browsers what happened: success (200), redirection (3xx), client errors like missing pages (4xx), or server failures (5xx).

How it works

Crawlers read status codes to decide what to do with a URL: index a 200, follow a 301 to its target, drop a 404 over time, and back off on 5xx errors. The codes are the primary technical language a site uses to communicate page state.

The ones that matter most for SEO are 200, 301, 302, 304, 404, 410, and 5xx. Misreporting them, such as serving a 200 for a missing page, confuses engines.

HTTP status codes vs the visible page

What a user sees and what the server reports can diverge. A page can display a friendly Not Found message while returning a 200 status, which tells crawlers the page is fine. The status code, not the visible content, is what engines act on, which is why soft 404s are a problem.

Why it matters for B2B

Status codes are the first thing to check when an AI engine stops citing a page. A page returning 5xx during crawls, redirecting unexpectedly, or serving soft 404s will be dropped from retrieval regardless of content quality. Your log files plus a status check are the fastest diagnosis of why a previously cited page went quiet.

200  OK           serve the page
301  Moved        permanent redirect (passes signals)
404  Not Found    page is gone
410  Gone         gone for good
503  Unavailable  temporary, retry later