llms.txt is a proposed convention for a plain-text file placed at the root of a website (e.g. `https://example.com/llms.txt`) that gives large language models a concise, structured summary of the site's content and purpose. It is analogous to `robots.txt` but aimed at AI crawlers and retrieval systems rather than traditional search bots. Publishers use it to help AI systems accurately represent their brand and products when generating answers. Adoption is still voluntary, but it has gained traction as [AI Overviews](/glossary/ai-overviews) and similar features grow in importance.