In 2024, a simple convention emerged for helping AI language models understand websites: llms.txt. It's a plain-text file placed in the root of your domain that tells AI tools what your site does, what content is available, and how to use it.
The concept is analogous to robots.txt (which tells search crawlers what to crawl) and sitemap.xml (which tells them what pages exist). llms.txt is designed for a different kind of consumer: the large language models that power ChatGPT, Perplexity, Claude, and similar tools.
What goes in llms.txt
A well-structured llms.txt file includes:
- A one-paragraph description of what your site or product does
- The key services or products you offer
- Pricing information (if public)
- Contact details
- Any context that helps an AI answer questions about your business accurately
The format is Markdown, clean, readable, no HTML tags. Think of it as a briefing document for an AI that knows nothing about you.
A minimal example
# Your Company Name > One paragraph description of what you do and who you serve. ## Services - Service one: brief description - Service two: brief description ## Pricing - Free tier: what's included - Paid plan: $X/month, what's included ## Contact Email: hello@yourcompany.com Website: https://yourcompany.com
How AI tools use it
When a user asks ChatGPT or Perplexity "what is [your company]?" or "what does [your product] do?", the AI may crawl your site to answer. If llms.txt is present, it's typically the first file read, giving the AI an accurate, curated understanding of your business before it tries to infer meaning from your HTML.
Without llms.txt, the AI guesses based on whatever it can extract from your pages. That extraction is often incomplete or misleading, especially for JavaScript-heavy sites where content isn't in the raw HTML.
Implementation
Create a file called llms.txt in the root of your repository. It needs to be accessible at https://yourdomain.com/llms.txt. No server configuration required, just upload the file.
The AuditIQ audit checks for llms.txt and includes it in your AEO score. If it's missing, it's typically one of the first fixes recommended, Low effort, High impact.