AI Search

llms.txt

llms.txt is a markdown file served at the root of a website (e.g. /llms.txt) that tells large language models what the site is about and which URLs to read for authoritative content.

Proposed at llmstxt.org, the format includes an H1 site name, a blockquote summary, and grouped link lists (`- [Title](/path): description`). A companion file, llms-full.txt, contains the full citable knowledge base. AI crawlers like ChatGPT, Claude, and Perplexity increasingly consume these files directly to avoid parsing JS-rendered pages — making them one of the highest-ROI GEO investments a site can make.

Related terms

Generative Engine Optimization (GEO)

Optimizing content so LLMs cite it verbatim in AI answers.

AI crawlers

Bots that gather web content for LLM training and citations.

robots.txt

A file that tells crawlers which URLs to fetch.

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