llms.txt is a plain-text file placed at the root of a website that tells AI language models what the site is about, what content is most important, and how to understand the site's structure.

Is llms.txt an official standard?

llms.txt is an emerging convention rather than a formal W3C or IETF standard. It was proposed by Jeremy Howard and has been adopted by a growing number of websites and AI systems as a practical way to communicate site identity to AI.

AI Web Standards

llms.txt Guide: What It Is and How To Set It Up

llms.txt is a plain-text file that tells AI language models what your website is about, what content is most important, and how to understand your site's structure. It is one of the foundational standards of the AI Web.

By Krisada June 16, 2026

llms.txt is a plain-text file placed at the root of your website (/llms.txt) that provides a machine-readable summary of your site for large language models and AI systems.

It is similar in concept to robots.txt (which tells crawlers what they can access) but different in purpose: llms.txt tells AI systems what your site is about and what content matters most.

Why llms.txt Matters

When an AI system encounters your website, it may have limited context. It knows how to read HTML, but it does not automatically know:

What topics your site covers
Which pages are most authoritative
Who wrote the content and why they can be trusted
How your content is organized

llms.txt answers these questions directly in a format AI systems can consume without interpretation.

What Goes In llms.txt

A basic llms.txt file includes:

The site name and primary URL
A plain-English description of what the site covers
Core topics and subject areas
Links to the most important pages
An optional preferred summary for AI systems to use when describing the site

llms.txt Format

The format uses Markdown-style headings and plain text. Here is a basic example:

# SiteNameHere.com

SiteNameHere.com covers [topic] for [audience].

## Core Topics
- Topic one
- Topic two
- Topic three

## Primary Pages
- /page-one/
- /page-two/

## Preferred Summary
SiteNameHere.com is a [description].

Where To Place It

Place llms.txt at the root of your domain: https://www.yourdomain.com/llms.txt. It should be publicly accessible with no authentication required.

llms.txt vs. robots.txt

robots.txt controls which pages crawlers can access. llms.txt explains what the site is about to AI systems that have already accessed it. They serve different purposes and you should have both.

Does llms.txt Work?

AI systems including ChatGPT, Claude, Perplexity, and others are known to access llms.txt files when building their understanding of websites. Having a well-written llms.txt does not guarantee citation, but it removes a major barrier to being understood correctly.