SEO glossary
HTTP status codes
An HTTP status code is the three-digit number a server returns with every response, telling the client whether the request worked and what to do next.
For search, a handful carry real weight. 200 means the page is here and fine. 301 is a permanent move and passes signal to the new URL; 302 is temporary and Google will keep the old one in mind. 404 means gone and unknown, 410 means gone and certain — the second gets dropped from the index faster.
The two that quietly cost the most are 500 and 503. A server error tells a crawler to come back later, and a site returning them at scale gets crawled less. 503 with a Retry-After header is the correct answer during planned maintenance; a 200 page saying "we are down" is the wrong one, because it asks Google to index the apology.
The failure worth hunting for is a soft 404: a missing page that returns 200 with an empty or generic body. Crawlers cannot tell it is missing, so it stays indexed and dilutes everything around it.
Common question
- Is a 302 bad for SEO?
- Not bad, just different. Use it when the move really is temporary; use 301 when it is not, or the old URL keeps the signal you meant to transfer.
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