What is Google-Extended?

Google-Extended is a robots.txt token that controls two Gemini uses of your content, and neither of them is Search:

• It is a control token, not a separate fetcher - Googlebot still does the crawling; Google-Extended decides what the crawled content may then be used for.
• It covers training AND grounding - Google says it manages whether content may train future Gemini models and be used “for grounding in Gemini Apps and Grounding with Google Search on Vertex AI”. Grounding is supplying the model with source material to answer from, so this reaches further than training alone.
• It does not touch your ranking - Google states it “does not impact a site’s inclusion in Google Search nor is it used as a ranking signal in Google Search” (Google Search Central).
• It does not control AI Overviews - those are part of Search, so your Googlebot rules are the only lever on them.

Eight per cent of Australian small-business sites mention Google-Extended in robots.txt^*. Blocking it costs you nothing in Search, but it does opt you out of being drawn on inside Gemini, so it is not the free decision it looks like.