llms.txt is a proposed plain-text index that tells LLMs which pages exist, what they cover, and where the markdown versions are.
llms.txt follows a simple markdown structure: an H1 site name, a blockquote summary, and link lists. It is not a Google ranking factor and many AI crawlers do not fetch it yet, so treat it as a supplement—not a replacement—for HTML, sitemaps and agentic discovery files such as Shopify's agents.md.
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