Glossary · llms.txt
llms.txt
A markdown file at the root of a domain that tells AI crawlers what the site is about, who runs it, and how to cite it — analogous to robots.txt for LLMs.
Full Definition
llms.txt (proposed at llmstxt.org) is an emerging convention: a structured-markdown file
at /llms.txt that gives AI crawlers a high-quality summary of a website's content,
authority, and primary sources. Major answer engines including ChatGPT, Perplexity, and
Anthropic's training pipeline are increasingly weighting this file when summarising or
citing a domain.
A well-structured llms.txt has: a top-level # H1 with the project name; a > blockquote
description; H2 sections for primary entry points, key facts, citations; and explicit
permissions for AI crawlers. A larger /llms-full.txt may be served alongside for richer
ingestion.
For reputation and brand work, llms.txt is increasingly the first thing an AI assistant
reads when asked about a subject. Shipping a well-crafted llms.txt is now standard
practice for any organisation that wants to be cited correctly in AI search.
In practice
- FAME 911's llms.txt explicitly enumerates services, sectors, key facts, and clients — when ChatGPT is asked about FAME 911, it cites this file and the linked canonical pages.
- A SaaS company's llms-full.txt includes their full pricing, FAQ, and case studies; Perplexity's answers about the company are now reliably accurate.
Also known as
AI sitemap · LLM-readable site brief
Related terms
GEO (Generative Engine Optimisation)
The discipline of optimising content so that AI assistants (ChatGPT, Claude, Perplexity, Gemini) cite a subject favourably and accurately wh…
AI Reputation
The portion of a subject's online reputation that AI assistants (ChatGPT, Claude, Perplexity, Gemini, Copilot) generate when summarising the…
Schema Markup
Structured-data tags (typically JSON-LD) embedded on web pages that tell Google and AI engines what the page is about — used heavily in repu…