GLOSSARY
User Agent
IN ONE SENTENCE
A user agent is the identity a client declares in its HTTP headers.
A user agent is the identity a client declares in its HTTP headers.
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In detail
It is the main clue for identifying AI crawlers, but only a clue — it can be spoofed or changed. ⚠️ Serving different content by user agent is high-risk: full HTML to conventional search engines and a shell to AI crawlers zeroes out every piece of content work.
Updated 2026-08-06