In short
llms.txt is a simple Markdown file you place at the root of your website (at /llms.txt) to give AI systems a clean, curated map of your most important content. Instead of forcing a model to crawl and guess at your HTML, ads and scripts, you hand it a short structured summary plus links to the pages that matter. It was proposed by Jeremy Howard of Answer.AI in September 2024, and it is to AI readers roughly what a sitemap or robots.txt is to search crawlers: a friendly, machine-first front door to your site.
What the file looks like
The format is deliberately small. A valid llms.txt starts with a single H1 holding your site or project name (the only strictly required part), followed by a blockquote with a one or two sentence summary, then optional sections. Each section is an H2 heading with a Markdown list of links, where every link is a title, a URL and a short description. In practice a good file curates roughly 15 to 60 of your canonical pages rather than listing everything.
# Your Site Name
> A one-line summary of what your site is and who it is for.
## Docs
- [Getting started](https://example.com/start): Set up in five minutes.
- [API reference](https://example.com/api): Every endpoint with examples.llms.txt vs llms-full.txt
There are two related files. llms.txt is the short, curated index of links and descriptions. The optional llms-full.txt concatenates the actual content of those pages into one large document, so a system that wants your whole corpus in a single request can grab it. Many sites publish both: the index for discovery and the full file for deep ingestion.
Does it actually help?
Adoption is real but uneven. Developer tools like Cursor and many documentation platforms read llms.txt, and Anthropic documents support for it, but as of 2026 Google and OpenAI have not officially committed to using it. So treat llms.txt as a low-cost, on-brand part of your AEO and GEO strategy rather than a guaranteed ranking lever: it makes your site cheap and unambiguous for AI to understand, and it complements (does not replace) good content and a sitemap.