AI Search Optimization
llms.txt, Explained: The File That Tells AI How to Read You
Somewhere in the last two years, a new kind of visitor started reading your website: AI systems deciding whether to recommend you. llms.txt is a small file that makes their job easier. Here's what it actually is, what it can and can't do, and how to set one up properly.
What it is
llms.txt is a plain-text Markdown file that lives at yourdomain.com/llms.txt. Proposed as an open standard in late 2024, it gives AI systems a curated, one-page orientation to your site: who you are, what you do, and where your most important pages live — without making them parse your navigation, your cookie banner, and nine layers of divs to figure it out.
Think of it as the difference between handing someone your business card and making them go through your filing cabinet.
What it is not
We'll be straight with you, because this is a category full of people who won't be: llms.txt is not a ranking switch. No AI provider has committed to treating it as one, adoption across AI crawlers is uneven, and anyone selling it as a guaranteed visibility boost is overselling.
So why bother? Three reasons. It costs almost nothing — thirty minutes, one file, zero risk. It's a readiness signal — a site that's organized for AI readers tends to be organized, period, and the act of writing one forces you to decide what actually matters on your site. And when an AI system does fetch it — some do today, more are likely to — the version of your business it reads is the one you wrote, not the one it reconstructed.
That's the honest case. It's insurance plus clarity, at the price of an email.
How the file is structured
The format is deliberately simple Markdown:
- An H1 with your business name — the only required element
- A blockquote summarizing what you do in one or two sentences
- H2 sections grouping annotated links: services, pricing, FAQs, contact
A service-business skeleton:
# Acme Plumbing
> Family-owned plumbing company serving the Indianapolis metro
> since 1998. Licensed, insured, 24/7 emergency service.
## Services
- [Water heater repair](https://acmeplumbing.com/water-heaters): same-day
service, all brands
- [Emergency plumbing](https://acmeplumbing.com/emergency): 24/7 dispatch
## About
- [Service area](https://acmeplumbing.com/areas): Indianapolis, Carmel, Fishers
- [Pricing](https://acmeplumbing.com/pricing): upfront, flat-rate
## Contact
- [Book online](https://acmeplumbing.com/book) or call (317) 555-0100Every link gets a short annotation — that's the part AI readers benefit from most. There's also an optional companion, llms-full.txt, which inlines full page content rather than links; for most service businesses the standard file is enough.
What to include (and leave out)
Include the pages that answer a buyer's questions: what you do, where you do it, what it costs, why you're credible, how to reach you. Leave out legal boilerplate, tag archives, and anything you wouldn't show a prospective customer in the first five minutes.
Two rules we hold clients to. Keep every claim in the file true and current — an llms.txt that says "24/7 service" when you stopped answering nights in 2024 is now feeding that error directly to AI systems. And update it when facts change, same day; it's the one file whose entire job is being accurate.
How it fits with robots.txt and schema
Three files, three jobs. robots.txt sets permissions — who may crawl what. Schema markup (JSON-LD) states machine-readable facts — your name, prices, hours, in a format engines parse. llms.txt provides orientation — a curated map, in prose. They don't overlap and they don't conflict; a well-set-up site has all three agreeing with each other.
You can see ours live at sightlinegrowth.co/llms.txt — we don't ship anything for clients we haven't run on ourselves.
Set it up this week
Write the file in any text editor, keep it under a page, have someone who knows the business fact-check every line, and publish it at the root. Then put a quarterly reminder on the calendar to re-read it.
Or start one step earlier: run the free Visibility Check and see how AI describes your business today — llms.txt is usually one of the first gaps it turns up.