llms.txt is a plain-text markdown file placed at the root of your website (like yoursite.com/llms.txt) that gives AI systems a curated, structured summary of what your site is about and where the important content lives. The standard was proposed in September 2024 by Jeremy Howard of Answer.AI, and adoption has been growing ever since.

How it differs from robots.txt and sitemap.xml

Your site probably already has two files that talk to machines, but they answer different questions:

• robots.txt answers "where may you go?" — it controls crawler access.
• sitemap.xml answers "what URLs exist?" — it lists pages with no context about what matters.
• llms.txt answers "what should you understand about us?" — it's a human-written map: what the business does, which pages carry the key facts, and how the content is organized.

Large language models work with limited context. When an AI system tries to understand your website, it can either parse dozens of cluttered HTML pages — navigation, cookie banners, scripts — or read one clean file written specifically for it. That's the entire idea of llms.txt.

What it looks like

# Acme Dental Clinic

> Family dental clinic in Austin, TX. Implants,
> orthodontics and pediatric dentistry since 2009.

## Services
- [Implants](https://acme.dental/implants): pricing and process
- [Invisalign](https://acme.dental/invisalign): teen and adult plans

## About
- [Team](https://acme.dental/team): doctors and credentials
- [Reviews](https://acme.dental/reviews): verified patient feedback

The format is simple: an H1 with the name, a blockquote with a one-paragraph summary, then sections with annotated links. Full spec at llmstxt.org.

Does your site actually need one?

Honest answer: not every AI system reads llms.txt today, and nobody can guarantee when full adoption comes. But the cost-benefit is lopsided: the file takes half an hour to write, doesn't interfere with anything, and every system that does read it gets a perfectly clear picture of your business — written by you, not guessed by a model from your HTML.

We treat it as cheap insurance with growing upside. Every Mentio GEO audit checks whether you have one, whether it's valid, and generates one if you don't.