HTTP Status Codes
In one line
HTTP status codes are the standard server responses (200, 301, 404, 500 and so on) that tell crawlers how to treat a request — and in SEO they directly steer indexing decisions.
Going deeper
HTTP status codes are the standard response set: 200 for success, 3xx for redirects, 4xx for client errors, 5xx for server errors. The SEO-relevant subset you deal with most is 200, 301, 302, 404, 410, 500 and 503.
A few traps come up repeatedly. Permanent moves should be 301 (or 308), temporary ones 302 (or 307); reaching for 302 by accident keeps link equity stuck on the old URL. During maintenance you want 503 with a Retry-After header so engines treat it as temporary — naked 500s can leak into indexing decisions.
AI search crawlers obey the same standard. GPTBot, PerplexityBot and ClaudeBot all read 200, 301 and 404 the same way, so good status-code hygiene is just as foundational for GEO as it is for classic SEO.
Related terms
410 Gone
410 Gone is the HTTP status that tells crawlers a page has been permanently removed — clearer than 404, because it explicitly says the page is not coming back.
SEOIndexability
Indexability is whether a crawled page is actually eligible to be stored in the search index — a page can be crawlable yet still not indexable.
SEOJavaScript SEO
JavaScript SEO is the discipline of making sure JS-rendered pages get crawled and indexed correctly — usually via some combination of SSR, prerendering and hydration.
SEOLog File Analysis
Log file analysis is the practice of inspecting raw server access logs to see exactly how search and AI bots crawl your site — the most direct, no-guesswork view of crawl behaviour.
SEOX-Robots-Tag
X-Robots-Tag is the HTTP response header version of the meta robots directive — useful when you need to control indexing for non-HTML assets like PDFs, images and other binaries.