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Glossary

What is a web crawler?

A web crawler is a bot that fetches pages automatically to build a search index or gather data, guided by robots.txt but not bound by it.

A web crawler is a bot that fetches pages automatically, usually to build a search index or gather data for some other system. It follows links from page to page on its own, without a person directing each request, and reads robots.txt to learn which paths it is invited to fetch.

Most requests for a file like llms.txt turn out to come from crawlers of this kind, not from AI assistants answering a specific question. Ahrefs' own analysis found that SEO audit tools and general crawlers made up most of the traffic to the llms.txt files it studied.

For the full breakdown of who actually requests these files, see what is an llms.txt file, a real one explained line by line.