Every single time you type a URL into your browser or click a link, your computer has a rapid, invisible conversation with the server hosting that website. The server responds to your request with a three-digit number known as an HTTP Status Code.
While human users rarely notice these codes unless something breaks (like a 404 error page), search engine crawlers like Googlebot rely entirely on these codes to understand the health, architecture, and indexability of your website.
The 5 Classes of Status Codes
- 1xx (Informational): The request was received, continuing process. (Rarely relevant for SEO).
- 2xx (Successful): The request was successfully received, understood, and accepted.
- 3xx (Redirection): Further action needs to be taken to complete the request.
- 4xx (Client Error): The request contains bad syntax or cannot be fulfilled.
- 5xx (Server Error): The server failed to fulfill an apparently valid request.
Crucial SEO Status Codes Explained
200 OK
This is the gold standard. It tells Googlebot: "The page exists, it loaded perfectly, please crawl and index this content." Every page you want ranking on Google must return a 200 status.
301 Moved Permanently
A 301 redirect is the most important tool in your arsenal. It tells Google: "This page has permanently moved to a new URL. Please transfer all ranking power (link equity) to the new destination." Use this when deleting old blog posts and merging them into newer guides.
302 Found (Temporary Redirect)
A 302 tells Google: "This page has moved, but only temporarily. Do not transfer the ranking power, and keep the original URL indexed." Use this sparingly, such as during short-term website maintenance or A/B testing. Leaving a 302 active for years is a massive SEO mistake.
404 Not Found vs. 410 Gone
A 404 indicates the page is missing. Google will eventually de-index a 404, but it might take months of re-crawling to confirm it is not a temporary glitch. A 410 Gone explicitly tells Google: "I deleted this page on purpose, and it is never coming back. Drop it from the index immediately."
How to Monitor Your Status Codes
Status codes often break quietly in the background after CMS updates or server migrations. You should run a monthly check using our HTTP Header Checker to ensure your critical money pages are returning clean 200 OKs, and verify that your old URLs are properly executing 301 redirects rather than deadly 404s.
