llms.txt
A plain text file at the site root describing what a site covers and which pages matter most, written for AI clients.
What it means
A short, human-written summary plus a curated list of the important URLs. It is a proposed convention rather than a standard, and support across AI systems is still uneven.
The part a short definition leaves out
Treat it as cheap insurance, not as something that moves a number. It takes twenty minutes to write and costs nothing to be wrong about. Anyone selling it as a ranking factor is selling something.
Where this comes from
See whether this is costing you anything
The inspection reports on this signal directly, alongside thirty-seven others, and tells you whether it is a quick fix on your site or something deeper.