What is llms.txt?

llms.txt is a Markdown file at the root of a website that tells AI agents and language models, in a curated way, who the operator is, what it offers and which pages carry its most important statements.

The layout follows a fixed format: only an H1 with the name is required; recommended are a blockquote as the framing sentence and H2 sections with link lists in the format "- [Title](URL): note". Unlike the sitemap, which lists everything, the file curates: it points to the pages where the citable answers live.

The file is a proposal, not a W3C standard, in version 2 since August 2026. Its effect on visibility has not been shown so far: measurements find hardly any requests from the search crawlers of ChatGPT and Perplexity, and Google explicitly ignores the file in Search. It is useful for AI agents that search a website on purpose.