Glossary · Crawlers and access
retrieval crawler
A crawler that fetches pages to answer a question being asked right now. Distinct from a training crawler by purpose, not by capability, and the two are often operated by the same company under different user-agents.
Crawlers and access
Who is fetching, whether they are who they claim, and what your rules actually permit.
user-triggered fetch · verified crawler · forged crawler identity · unverifiable · robots.txt · user-agent group · AI opt-out · Content-Signal · crawl budget · cloaking · challenge page at 200 · uniform refusal · nonexistent-path control · blocked render resource · off-host redirect · homepage refused · FCrDNS · Crawler trap · Conditional request · ASN blocking · operator feed · residential proxy · Google-Extended · Google-Agent · GPTBot vs OAI-SearchBot · ClaudeBot vs Claude-User · PerplexityBot vs Perplexity-User · CCBot · Bytespider · agentic traffic · crawler classification
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