Gemini sits on top of Google Search, so most of what helps you in Google helps you in Gemini. One setting doesn’t follow that rule, and about one in eight top websites has switched it on.
Google’s developer documentation describes the mechanism. With grounding on, “the model analyzes the prompt and determines if a Google Search can improve the answer”, and if so it “automatically generates one or multiple search queries and executes them”, then links parts of its answer to the pages it used (Gemini API docs). In the Gemini app, those links appear under a Sources button, and a separate double-check feature uses Google Search to highlight statements it can and can’t corroborate (Gemini Apps Help).
Two practical consequences. First, your pages have to be indexed by Google and answer the search Gemini runs, which is a few words, not the user’s whole question. Second, the brands Gemini names often come from the pages that rank for those words: comparison articles, review sites and category pages.
Google-Extended is a robots.txt token, not a crawler. Google says it lets publishers manage whether content Google crawls can be used to train Gemini models and for grounding in Gemini Apps and Vertex AI, and that it “does not impact a site’s inclusion in Google Search nor is it used as a ranking signal” (Google Search Central).
So a site that blocks Google-Extended to keep out of AI training has also asked Google not to ground Gemini’s answers in its pages, while ranking in Search exactly as before. In our October 2026 crawl, 579 of 4,762 top sites (12.2%) block Google-Extended, and 508 of them (88%) still let Googlebot in. For a publisher protecting its archive, that may be the point. For a brand that wants Gemini to describe it accurately, it works against you.
AI Overviews and AI Mode are different again: they are part of Google Search, so Google-Extended doesn’t affect them. Our AI Overviews guide covers the controls that do.
Yes, when it decides a search will improve the answer. Google’s documentation says Gemini generates one or more search queries, runs them, and links parts of its answer to the sources it used. In the Gemini app those links appear under Sources.
No. Google says Google-Extended doesn’t affect inclusion or ranking in Google Search. It does control whether your content is used to train Gemini models and to ground answers in Gemini Apps and Vertex AI.
In our October 2026 crawl of the Tranco top 10,000, 12.2% of 4,762 sites with a readable robots.txt blocked Google-Extended from their homepage, and most of them still allowed Googlebot.
Ask Gemini the questions a buyer would ask, several times and in several phrasings, and note whether you’re named and which sources it shows. Mentioned runs Gemini on our key, alongside Claude and ChatGPT, and tracks the same questions every week.
Related guides: ChatGPT, Claude, Perplexity and Copilot.