llms.txt explained: the file that tells AI what your site is about

llms.txt is a plain text file hosted at yoursite.com/llms.txt that provides AI language models with a concise, human-readable description of who you are, what you do, and what your key content covers. Think of it as a robots.txt for AI understanding — not access control, but context.

The format is simple. It typically includes your organisation name and description, a summary of your main services or products, links to key pages you want AI models to prioritise, and any specific guidance about how to accurately represent your brand. It doesn't need to be long — a focused 200-400 word file is more useful than an exhaustive one.

Several major AI systems now actively reference llms.txt files when building their understanding of a site. Having one doesn't guarantee citation, but it does reduce the risk of AI models misrepresenting your brand — which is increasingly common as AI search scales. If you've ever seen ChatGPT describe your company inaccurately, an llms.txt is part of the fix.

Creating an llms.txt is a 30-minute task. Write a clear description of your organisation, list your key services with brief descriptions, link to your most important pages, and include any factual corrections to common misrepresentations you've encountered. Host it at the root of your domain and submit it to the AI crawlers that support it.