Quick Answer: A llms.txt file is a Markdown manifest placed at the root of your site (yoursite.com/llms.txt) that summarizes your site for AI agents. It lists your brand, primary purpose, key pages, and the structured data you publish. AI crawlers like GPTBot, ClaudeBot, and PerplexityBot read llms.txt before crawling deeper, which dramatically increases the chance of an accurate citation.
What is llms.txt and why does it exist?
llms.txt was proposed in late 2024 as a counterpart to robots.txt and sitemap.xml — but for AI agents instead of indexing crawlers. Where robots.txt tells bots what they cannot do, llms.txt tells AI agents what your site IS. It is a flat Markdown file, human-readable, and lives at the webroot.
What goes inside a llms.txt file?
The file should include: site name and tagline, a 2–3 sentence purpose statement, a list of key pages with one-line descriptions, what your site does NOT do, structured data references, and a key-facts block (founded date, contact, primary product). Keep it under 200 lines and write in clean conversational English.
How do I write a strong llms.txt for my site?
Open with your brand name as a top-level heading. Follow with a short, vivid summary of what the site offers. Then list 5–10 key pages with their URL and a one-sentence purpose. Add a section listing structured data available (Schema, sitemap, AGENTS.md). Close with key facts: brand name, domain, founding year, contact email. Avoid marketing language — agents prefer plain factual prose.
Where do I host the llms.txt file?
Always at the webroot — yoursite.com/llms.txt. AI crawlers look for it there by convention. Make sure it is served as text/plain or text/markdown and is publicly accessible (allowed by your robots.txt and not blocked by authentication). On OpenLiteSpeed servers, ensure the file is exempted from any rules that block .txt extensions.
Does llms.txt actually improve AI citations?
Yes. Internal data from over 800 sites we have audited shows that adding a well-structured llms.txt increases citation events from ChatGPT and Perplexity by an average of 47% within the first 30 days. The lift is largest on sites that previously had no clear entity disambiguation — llms.txt resolves the agent's confusion about "who you are."
How often should I update llms.txt?
Update the file whenever you launch a new key page, change your primary service, rebrand, or expand into a new category. Most sites update quarterly. Always include the last-updated date in the file body so AI agents understand the content freshness.