What is Google AI Overviews, AI Mode and Gemini?

AI Overviews and AI Mode draw on the Google Search index: a page must be indexed and eligible for a snippet to appear as a supporting link^[1]. Grounding in Gemini Apps and in Grounding with Google Search on Vertex AI is controlled separately through the Google-Extended token^[3]. Same operator as Google Search; no syndication from another engine is described.

What the figures measure: StatCounter's AI chatbot market share, October 2026. StatCounter does not describe how it measures AI chatbot share on the pages read, so no method is claimed here. StatCounter's label is “Google Gemini”; this page is about Google AI Overviews, AI Mode and Gemini. Source: StatCounter Global Stats, licensed CC BY-SA 3.0.

Stance recordedSays no special markup is needed

Google says a page needs nothing beyond normal Search eligibility: "There are no additional technical requirements." It adds that no special schema.org markup is needed for AI Overviews or AI Mode. It does not say whether structured data is used when an answer is composed.^[1]

“Not documented” means the pages read do not say; it does not mean the format is ignored.

The research records 1 rich result type for Google AI Overviews, AI Mode and Gemini: 1 active. Each entry shows the schema.org types it is documented for, where the research records them. Valid markup can make a page eligible; it does not guarantee the result.

The research lists 5 crawler tokens for Google AI Overviews, AI Mode and Gemini: the names a site uses in robots.txt rules, with what each one does where the source says.

• Googlebot

  Google Search crawler. AI Overviews and AI Mode use the Search index, and the AI features page calls robots.txt rules for Googlebot the control for crawl access to Search. The full Google crawler list is on the Google Search page. follows robots.txt.^[1]

• Google-Extended

  Robots.txt product token, not a crawler: it has no separate HTTP user agent. Controls whether crawled content may be used to train future Gemini models and for grounding in Gemini Apps and Grounding with Google Search on Vertex AI. No effect on Search inclusion or ranking. A control token that does not crawl.^[3]

• Google-CloudVertexBot

  Crawls requested by site owners who are building Vertex AI Agents. No effect on Google Search or other products. The page gives a user agent substring equal to the token, not a full string. robots.txt is presented as the control, with no statement that the crawler follows it.^[3]

• Google-GeminiNotebook

  User-triggered fetcher. Requests the URLs that Gemini Notebook users add as sources. The former token is Google-NotebookLM, for which the page gives August 2026 as the end of support. may ignore robots.txt (fetches a person asked for).^[4]

• Google-Agent

  User-triggered fetcher. Used by agents hosted on Google infrastructure that browse the web and act at a user's request. IP ranges are published in a file named user-triggered-agents.json. Google says it is testing Web Bot Auth with the identity https://agent.bot.goog. may ignore robots.txt (fetches a person asked for).^[4]

The research records no markup testing tool of its own for Google AI Overviews, AI Mode and Gemini.

Guidelines

eligibility

To appear as a supporting link in AI Overviews or AI Mode a page must be indexed and eligible to be shown in Google Search with a snippet. Meeting the requirements does not guarantee crawling, indexing or serving.^[1]

structured data

No new machine-readable files, AI text files or markup are needed, and there is no special schema.org structured data to add. Google still recommends that structured data match the visible text on the page.^[1]

preview controls

nosnippet, data-nosnippet, max-snippet and noindex limit what is shown from a page in Search, including in these AI features. After a change, recrawling can take several days to several months.^[1]

crawl control

robots.txt rules for Googlebot are the control for how a site is crawled for Search, and so for these AI features.^[1]

ai use controls

Google-Extended is a robots.txt product token. It controls whether crawled content may be used to train future Gemini models and for grounding in Gemini Apps and Grounding with Google Search on Vertex AI. It does not affect inclusion or ranking in Google Search.^[3]

aipref

Google says it intends to support the AIPREF training preference signal, written as the robots.txt user agent __usage_ai-training, in early 2027.^[3]

reporting

Traffic from AI features is counted in the Search Console Performance report under the Web search type.^[1]

query fan-out

Both features may run several related searches across subtopics and data sources to build one response, which can surface a wider set of links than a classic search.^[1]

blog advice

A 2025 blog post says structured data makes pages eligible for certain search features and rich results, that content in markup must also be visible on the page and that markup should be validated. It advises keeping Merchant Center and Business Profile data current. It does not say structured data affects AI Overviews or AI Mode directly.^[2]

user fetch

Google says its user-triggered fetchers, as a group, "generally ignore robots.txt rules" because a user asked for the fetch.^[4]

These claims about Google AI Overviews, AI Mode and Gemini came up in the research, but no page that could be read confirms them. They are kept apart, and nothing above rests on them.

• AI Overviews and AI Mode are available in every country and language.

  Why it is open: The * in countries is a placeholder, not a verified global footprint.

  How it was checked

  The AI features page^[1] gives no availability list and the researcher did not collect one. The Google availability research covers rich results only.

• Google uses structured data when it composes AI Overviews or AI Mode answers.

  Why it is open: No primary statement either way.

  How it was checked

  Read the AI features page^[1] and the 2025 blog post^[2]. Both say no special markup is needed; neither says whether existing markup is used in the answer.

The pages the research used for Google AI Overviews, AI Mode and Gemini, numbered as cited above. Accessed November 10, 2026 unless shown.

1. 1.AI features and your website · Google Search Central
2. 2.Google Search Central blog post of 2025-05-21 on succeeding in AI search (exact title not captured) · Google Search Central · updated May 21, 2025
3. 3.List of Google's common crawlers (older path; the Google Search research records the same page under /crawling/docs/crawlers-fetchers/) · Google Search Central
4. 4.List of Google user-triggered fetchers (older path; the Google Search research records the same page under /crawling/docs/crawlers-fetchers/) · Google Search Central

Market share figures: StatCounter Global Stats, AI chatbot market share, October 2026, licensed CC BY-SA 3.0.