Glossary
llms.txt
A plain-text file at the root of your site that tells AI crawlers what your site is and points them to the pages that matter most.
Definition
llms.txt is an emerging standard (defined at llmstxt.org) for a Markdown file served at /llms.txt. It gives AI crawlers a concise, curated map of your site: a title, a short summary, and lists of your most important pages grouped under headings, so an engine can find your key content without wading through navigation, scripts, and boilerplate. It sits alongside robots.txt and sitemap.xml as part of a site's machine-readable layer, but where those speak to search crawlers, llms.txt speaks to language models. A well-formed file follows a strict shape: a single H1 title, a blockquote summary, then H2 sections of links. Get that shape wrong, or omit the file entirely, and engines fall back to guessing.
Example
A SaaS company adds an /llms.txt listing its product, pricing, and docs pages under clear headings, giving ChatGPT and Perplexity a clean map of what to cite instead of leaving them to crawl the raw HTML.
Related terms
Generative Engine Optimization (GEO)
The practice of optimizing your brand and content to be cited, recommended, and described favorably by generative AI engines.
Answer Engine Optimization (AEO)
The practice of optimizing your brand and content so that AI answer engines cite you when users ask direct questions.
Schema Markup
Structured data added to your pages (in JSON-LD format) that tells search engines and LLMs exactly what your content is about.
Large Language Model (LLM)
The underlying AI model that powers AI engines: examples include GPT-5, Gemini 3, Claude Sonnet 4.6, and Grok 4.
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