# Google AI Overviews: How They Choose and Cite Sources > What Google AI Overviews are, what Google documents about eligibility, fan-out and controls, what the click studies found, and what is known for Perth. Source: https://aiseoperth.net.au/google-ai-overviews/ --- Reference # Google AI Overviews: how they choose and cite sources Author Dorian Menard, founder of Search Scope Published 9 September 2026 Reading time 8 min Google AI Overviews are generative summaries shown at the top of some Google Search results, with links to supporting pages. Google states they are a core Search feature drawn from the normal Search index: a page must be indexed and eligible for a snippet to be a supporting link, there are no additional requirements, and no special markup is needed. AI Overviews are available in Australia, so they appear for Perth searches. ## Key facts Key facts about Google AI Overviews Fact Detail Evidence What they are Generative AI summaries in Google Search results with links to supporting websites, shown when Google's systems determine generative AI can be especially helpful. DOCUMENTED Eligibility A page must be indexed and eligible to be shown in Google Search with a snippet. No additional technical requirements. DOCUMENTED Retrieval May use query fan-out: multiple related searches across subtopics and data sources. AI Mode and AI Overviews may use different models and techniques. DOCUMENTED Controls Googlebot robots.txt rules govern crawling; nosnippet, data-nosnippet, max-snippet and noindex limit what is shown. Google-Extended does not affect Search. DOCUMENTED Measurement Traffic from AI Overviews and AI Mode is included in the Search Console Performance report under the Web search type, not reported separately. DOCUMENTED Frequency (US) 18% of Google searches in March 2025 produced an AI summary; 88% of summaries cited three or more sources (Pew, 900 US adults). TESTED Click effect Users who saw a summary clicked a traditional result in 8% of visits versus 15% without one (Pew). Ahrefs found a 34.5% lower average CTR for the top-ranking page on informational keywords with an AI Overview (300,000 keywords). TESTED Australia Google lists Australia among countries where AI Overviews are available. AI Mode rolled out in Australia in English on 8 October 2025. DOCUMENTED ## What an AI Overview is DOCUMENTED Google describes AI Overviews as a feature that shows “when our systems determine that generative AI can be especially helpful”, for example to “quickly understand information from a range of sources”, with “key information and links to dig deeper”. They are “a core Google Search feature, like knowledge panels” and cannot be turned off, though the Web filter shows only text links. Google also states plainly that “AI Overviews can and will make mistakes”. For a site owner the important word is core. An AI Overview is not a separate product with its own index, submission path or ranking. It is Search, composing. ## Eligibility and what Google says about optimisation DOCUMENTED Google’s documentation for site owners is unusually direct. “The best practices for SEO remain relevant for AI features in Google Search. There are no additional requirements to appear in AI Overviews or AI Mode, nor other special optimizations necessary.” To be a supporting link, “a page must be indexed and eligible to be shown in Google Search with a snippet”. “You don’t need to create new machine readable files, AI text files, or markup to appear in these features. There’s also no special schema.org structured data that you need to add.” And the standing caveat: meeting every requirement “doesn’t mean that Google will crawl, index, or serve its content. Indexing and serving isn’t guaranteed.” The fundamentals Google lists are crawling allowed in robots.txt and by any CDN or hosting layer, content findable through internal links, good page experience, important content in text form, structured data matching the visible text, and current Merchant Center and Business Profile information. ## How sources are retrieved DOCUMENTED “Both AI Overviews and AI Mode may use a query fan-out technique, issuing multiple related searches across subtopics and data sources, to develop a response.” As the response is generated, Google’s models “identify more supporting web pages”, producing “a wider and more diverse set of helpful links” than a classic search. Google adds that “AI Mode and AI Overviews may use different models and techniques”. INFERRED The inference this publication draws, and labels: a page can be retrieved by a fan-out for a sub-question the searcher never typed, which is why breadth of coverage around a subject can matter more for AI Overviews than a single page aimed at the head term. Google does not publish which sub-queries it issues or how it weighs the results. ## What selection favours Google has not published a ranked list of factors for which retrieved pages an overview draws on. Anything presented as one is inference. What can be said from the documentation is that ordinary Search eligibility is the gate, that preview controls narrow what is shown, and that Google’s advice for succeeding is its long-standing advice: “focus on your visitors and provide them with unique, satisfying content”. Everything more specific belongs to observation, which is what the [planned Perth source study](https://aiseoperth.net.au/research/) exists for. ## What the click studies found TESTED [Pew Research Center](https://www.pewresearch.org/short-reads/2025/07/22/google-users-are-less-likely-to-click-on-links-when-an-ai-summary-appears-in-the-results/) analysed the browsing data of 900 US adults for March 2025. 18% of Google searches in the study produced an AI summary. Users who saw one clicked a traditional result link in 8% of visits, against 15% for users who did not; they clicked a link inside the summary in 1% of visits. 88% of summaries cited three or more sources, and only 1% cited a single source. TESTED [Ahrefs](https://ahrefs.com/blog/ai-overviews-reduce-clicks/) compared 300,000 informational keywords, half of which triggered an AI Overview in March 2025, using Search Console click-through rates for March 2024 (before the US rollout) and March 2025. Its estimate was that the presence of an AI Overview reduced the click-through rate of the top-ranking page by about 34.5%, relative to what the informational-keyword trend predicted. Ahrefs notes 99.2% of keywords that triggered an overview in its data were informational. Both studies are US-based and pre-date AI Mode. No equivalent Australian panel study is known to this publication, and neither study says anything about Perth. ## AI Overviews and AI Mode DOCUMENTED AI Mode is the conversational surface: “an AI-powered search experience for those who want to go deeper”, where “people can ask nuanced questions that might have previously taken multiple searches”. The same eligibility rule applies, the same fan-out may be used, and Google says the two “may use different models and techniques”. Google Australia announced AI Mode’s rollout “in Australia in English” on 8 October 2025, “using a custom version of our advanced Gemini models”. This publication records the two surfaces separately in its [methodology](https://aiseoperth.net.au/methodology/#platforms) because their citation behaviour can differ. ## Controls and measurement DOCUMENTED Because AI is “integral to how Search functions”, the robots.txt rules for Googlebot are the control over crawling for these features. To limit what is shown, Google names nosnippet, data-nosnippet, max-snippet and noindex, and says “more restrictive permissions will limit how your content is featured in our AI experiences”. Google-Extended, the token for Gemini training and grounding, “does not impact a site’s inclusion in Google Search nor is it used as a ranking signal”. DOCUMENTED Sites appearing in AI Overviews and AI Mode “are included in the overall search traffic in Search Console”, within the Performance report’s Web search type. There is no separate AI Overviews report, so a Perth site cannot read its overview clicks directly from Search Console. ## How AI Overviews apply in Perth DOCUMENTED AI Overviews are available in Australia and AI Mode has been available in Australia since 8 October 2025, so both appear for searches made in Perth on google.com.au. HYPOTHESIS Which Perth queries trigger an overview, and which sources those overviews cite, is not documented anywhere and has not been measured by this publication yet. The planned study records, per Perth prompt, whether an overview appeared, every cited source, and the organic results beneath it, so the overlap between cited sources and organic rankings can be reported as a count rather than assumed. ## What is documented and what is inferred - **Documented:** eligibility; no special markup; query fan-out; preview controls; Search Console reporting; availability in Australia; AI Mode’s Australian launch date. - **Tested:** Pew’s frequency and click figures; Ahrefs’ CTR estimate; both US. - **Inferred:** that fan-out rewards coverage of sub-questions. - **Not established:** any factor list for source selection; any Perth trigger rate or source mix. ## Related concepts - [ Reference Answer Engine Optimisation Being the extracted answer. ](https://aiseoperth.net.au/answer-engine-optimisation/) - [ Reference AI search optimisation The retrieval mechanism across platforms. ](https://aiseoperth.net.au/ai-search-optimisation/) - [ Reference Gemini SEO Google's assistant, a different surface. ](https://aiseoperth.net.au/gemini-seo/) - [ Guide Why pages are not appearing in AI Overviews Diagnostic order for absence. ](https://aiseoperth.net.au/guides/not-appearing-in-ai-overviews/) - [ Guide AI Overviews and organic traffic What to expect from clicks. ](https://aiseoperth.net.au/guides/ai-overviews-organic-traffic/) ## Related research - [ Planned study Google AI Overviews Perth Source Study Which Perth prompts trigger an overview and what it cites. ](https://aiseoperth.net.au/research/) ## Sources 1. [AI features and your website](https://developers.google.com/search/docs/appearance/ai-features), Google Search Central (read 9 September 2026) DOCUMENTED 2. [Top ways to ensure your content performs well in Google's AI experiences on Search](https://developers.google.com/search/blog/2025/05/succeeding-in-ai-search), Google Search Central Blog, 21 May 2025 (read 9 September 2026) DOCUMENTED 3. [Find information in faster and easier ways with AI Overviews in Google Search](https://support.google.com/websearch/answer/14901683), Google Search Help (read 9 September 2026) DOCUMENTED 4. [Google Search: Introducing AI Mode in Australia](https://blog.google/intl/en-au/products/explore-get-answers/ai-mode-in-australia/), Google Australia Blog, 8 October 2025 (read 9 September 2026) DOCUMENTED 5. [Google crawlers and fetchers (Google-Extended)](https://developers.google.com/search/docs/crawling-indexing/google-common-crawlers), Google Search Central (read 9 September 2026) DOCUMENTED 6. [Google users are less likely to click on links when an AI summary appears in the results](https://www.pewresearch.org/short-reads/2025/07/22/google-users-are-less-likely-to-click-on-links-when-an-ai-summary-appears-in-the-results/), Pew Research Center, 22 July 2025 (read 9 September 2026) TESTED 7. [AI Overviews Reduce Clicks by 34.5%](https://ahrefs.com/blog/ai-overviews-reduce-clicks/), Ahrefs (Ryan Law, Xibeijia Guan), 17 April 2025 (read 9 September 2026) TESTED 300,000 keywords, informational intent, March 2024 versus March 2025, US rollout. On this page - [Definition](#definition) - [What an AI Overview is](#what-an-ai-overview-is) - [Eligibility and what Google says about optimisation](#eligibility-and-what-google-says-about-optimisation) - [How sources are retrieved](#how-sources-are-retrieved) - [What selection favours](#what-selection-favours) - [What the click studies found](#what-the-click-studies-found) - [AI Overviews and AI Mode](#ai-overviews-and-ai-mode) - [Controls and measurement](#controls-and-measurement) - [How AI Overviews apply in Perth](#how-ai-overviews-apply-in-perth) - [What is documented and what is inferred](#what-is-documented-and-what-is-inferred) - [Sources](#sources) Evidence labels Claims on this page are labelled DOCUMENTED, OBSERVED, TESTED, INFERRED or HYPOTHESIS. [What the labels mean](https://aiseoperth.net.au/methodology/#evidence-labels). Published by Search Scope AI SEO Perth is published by Search Scope, a Perth SEO consultancy founded by Dorian Menard. Search Scope provides commercial SEO and AI search optimisation services; this website is maintained as its specialist Perth AI search research and reference publication. [Search Scope](https://searchscope.com.au/)