What is llms.txt?
llms.txt is a proposed plaintext file at a site's root that gives AI models and agents a clean, curated summary of the site — what it is, who it's for, and links to its most important pages — in a format built for machine reading rather than human browsing.
llms.txt is a community-proposed convention, modeled on the decades-old robots.txt, that lives at yourdomain.com/llms.txt. Instead of controlling crawler access, it gives any AI system a short, structured, markdown-style brief: what the product or business is, who it serves, its pricing, and a curated list of links (docs, key articles, tools) that matter most. The goal is to hand a model exactly the context a human would explain in a two-minute pitch, instead of making it infer that from scattered HTML.
It matters for GEO because LLMs and retrieval systems are far more likely to describe a brand accurately when they can find one authoritative, unambiguous summary rather than reconstructing facts from marketing copy, out-of-date directory listings, or a competitor's comparison page. A well-written llms.txt reduces the chance an assistant hallucinates your pricing or confuses you with a similarly-named company.
Adoption is still emerging and no major AI vendor has committed to treating llms.txt as an authoritative signal the way search engines treat robots.txt or sitemap.xml — but it costs almost nothing to publish, several developer tools already read it, and it's a clean, low-risk piece of GEO hygiene alongside structured data and crawler access.