Quick Answer: llms.txt is a plain Markdown file placed at the root of your website (e.g., yoursite.com/llms.txt) that gives AI crawlers a structured, human-readable map of your site's most important content, your brand description, and how AI agents should interpret your content. It is becoming a de facto standard for AEO-ready sites.

llms.txt is one of the simplest and highest-leverage AEO investments you can make. The file takes minutes to create, costs nothing to deploy, and meaningfully improves how AI engines understand and cite your content.

What does llms.txt do?

llms.txt is conceptually similar to robots.txt or sitemap.xml — a single file at the root of your domain that AI crawlers can read to understand your site. But where robots.txt tells crawlers what they can and cannot access, llms.txt tells them what your site is about and what content matters most.

The file is written in Markdown, the format LLMs are most comfortable parsing. It typically includes:

  • Your brand name and one-line description
  • What your site does and what services it offers
  • Links to your most important pages, organized by section
  • References to your structured data, sitemaps, and other AI-relevant files
  • Any constraints or guidance for how AI agents should use your content

Why does llms.txt matter for AEO?

AI crawlers are bandwidth- and time-budgeted. They cannot fully crawl every page of every site, especially large sites. An llms.txt file tells the crawler what to prioritize, dramatically improving the odds that your most important content gets ingested, indexed, and cited.

Beyond crawl efficiency, llms.txt improves AI comprehension. When a crawler arrives at your site, it has to figure out what kind of business you are, what your category is, what content you have, and what your structure looks like. An llms.txt file answers all of those questions in a single short document, removing ambiguity and increasing the confidence with which AI engines cite you.

What does an llms.txt file look like?

A minimal llms.txt looks like this:

# The AEO Hub

Directory and resource hub connecting businesses with vetted Answer Engine Optimization (AEO) agencies, freelancers, and tools.

## What this site does

The AEO Hub helps businesses find vetted AEO experts who can get them cited in ChatGPT, Perplexity, Google AI Overviews, and voice search results.

## Key pages

- [Home](/) — Directory hub overview
- [Agencies](/agencies.php) — Browse 200+ vetted AEO agencies
- [Tools](/tools.php) — AEO software reviews and comparisons
- [Blog](/blog.php) — AEO strategies and analysis

## Structured data

- Sitemap: /sitemap.xml
- Schema: JSON-LD on all pages
- AEO entry: /AGENTS.md

How do I create an llms.txt for my site?

Three steps:

  1. Draft the file in Markdown. Cover the sections above. Keep it focused and concise — under 1,500 words is ideal.
  2. Place the file at /llms.txt. It must live at the root of your domain to be discovered.
  3. Reference it in your <head>. Add <link rel="alternate" type="text/markdown" href="/llms.txt"> and <meta name="ai-content-declaration" content="/llms.txt"> to every page.

Do AI engines actually use llms.txt?

Adoption is growing. Some AI engines explicitly use llms.txt as a discovery signal; others do not yet but likely will. The cost of deploying llms.txt is so low and the upside so meaningful that it is worth shipping regardless.

For a free downloadable llms.txt template, see our llms.txt Template resource.