The numeric reply a server gives for every page request — 200 means OK, 3xx is a redirect, 4xx means not found or forbidden, 5xx means a server error.
Every time a browser or crawler asks for a page, the server answers with a status code. 200 is healthy. 3xx is a redirect (the page moved). 404 (a 4xx) means the page doesn't exist; 403 means access is blocked. 5xx means the server itself failed. Crawlers treat these very differently — a 200 page can rank, a 404 can't, and repeated 5xx errors can make Google crawl your site less.
Status problems are easy to miss because they're invisible in a browser unless you look: a soft 404 returns a 200 for an effectively empty page, a broken internal link points at a 404, or a page that should redirect returns the wrong code. Each quietly wastes crawl budget or strands a page.
CommandSEO checks the status code of every page it audits and flags broken (4xx), error (5xx), and redirect responses, then re-verifies after you fix them so a page that should be a healthy 200 actually is.
What to do about it
Aim for a clean 200 on every page you want ranked. Fix or redirect 404s that have inbound links or traffic, resolve 5xx errors with your host, and make sure pages that moved return a proper 301. Re-verify in CommandSEO to confirm the status is clean live.
Common questions
What does a 404 error mean for SEO?
A 404 means the page doesn't exist, so it can't rank and any links pointing to it are wasted. Occasional 404s are normal; for important URLs, restore the page or 301-redirect it to the closest relevant live page.