llms.txt is a proposed plain-text standard file, placed at a website’s root (/llms.txt), that gives AI engines a curated, machine-readable index of the site’s most important content — in Markdown, with links and short descriptions. It’s an AI-era cousin of robots.txt and sitemap.xml.
The goal is to help large language models find and cite the right pages instead of guessing from a full crawl. Adoption is growing among AI-forward sites, though major engines have not publicly confirmed that they read it, so it’s best treated as a low-cost, forward-looking signal rather than a guaranteed ranking factor.
llms.txt is one tactic within Generative Engine Optimization. The guide below shows exactly what goes in the file, with a real working example served from this domain.
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What is llms.txt (with example)