Direct answer
Status codes describe the outcome of a request. A useful page returns 200, a missing page 404 or 410, a permanent move 301/308, and a temporary move 302/307.
Practical steps
- Map real content states.
- Return status at the server boundary.
- Keep redirects direct and bounded.
- Test headers and rendered experience together.
Common mistakes
- Soft 404s returning 200.
- Redirecting every missing URL home.
- Using permanent redirects for experiments.
Limitations
- A correct status does not ensure indexing.
- Caching and intermediaries can delay observations.
Primary sources
- Understand the JavaScript SEO basics — Google Search Central; 2026-03-04; 2026-08-14.