llms.txt is a proposed convention — like robots.txt — for a machine-readable file at the root of a website that helps large language models understand the site's content, structure, and entity information.
The file typically includes: a one-paragraph site description, key services or products, notable authors, top-level pages, and links to structured resources. AI crawlers (GPTBot, ClaudeBot, PerplexityBot, GoogleOther) can read it to build a faster and more accurate representation of the site.
It is not (yet) an official standard, but adoption is growing rapidly in the SEO and content-agency space. nagrosolutions.com publishes /llms.txt at the root as part of our GEO strategy.