What Are GEO, AEO and AIO? AI Search Terms Explained

The short answer

What is GEO? Generative engine optimization, and where the term came from

The paper's opening claim: "We propose Generative Engine Optimization, the first general optimization framework for website owners to optimize their websites for generative engines." [2]

How the test worked. The researchers built a benchmark of 10,000 queries, fetched only the top five Google results for each query, and had GPT-3.5 write the answers [2]. They then rewrote the source pages nine different ways and measured visibility with two metrics, Position-Adjusted Word Count and Subjective Impression [2].

What they found:

• The three best tactics, Cite Sources, Quotation Addition and Statistics Addition, "achieved a relative improvement of 30-40% on the Position-Adjusted Word Count metric and 15-30% on the Subjective Impression metric." [2]
• Lower-ranked pages gained the most: Cite Sources raised visibility 115.1% for pages ranked fifth, while the top-ranked page's visibility fell 30.3% on average [2].
• In a live test on Perplexity, Quotation Addition improved visibility 22%, and keyword stuffing did 10% worse than the unchanged pages [2].

Read it as evidence, not a promise. It was a lab engine built on GPT-3.5, and the authors say: "owing to the black-box nature of search engine algorithms, we didn't evaluate how GEO methods affect search rankings." [2] Anyone quoting "GEO boosts visibility 40%" as a client outcome is overstating a lab result.

What is AEO? Answer engine optimization

Google's question to owners, in full: "If they have advice on optimizing for AI experiences (also known as "AEO" "GEO" services), is their advice aligned with Google Search's official guidance on optimizing for generative AI features?" [7]

Where AEO advice differs, it is mostly about structure, and the platforms disagree. Microsoft says AI assistants break content into smaller pieces and, with question-and-answer pairs, "can often lift these pairs word for word" [5]. Google says: "There's no requirement to break your content into tiny pieces for AI to better understand it." [1] A page that answers each common question in plain, complete sentences satisfies both.

AEO is also about more than your own site. In Ahrefs' study of 75K brands, brand mentions across the web correlated with AI Overview visibility at 0.664, against 0.218 for backlinks [8]. That is a correlation, not proof of cause, but it explains why reviews, press and directory listings keep coming up in AEO advice.

AIO: AI Overviews and "AI optimization"

AI Overviews grew fast: by May 2025 they were available in more than 200 countries and territories and more than 40 languages, and by July 2025 Alphabet reported more than 2 billion monthly users [9][10]. Google's AI Mode is a separate experience that reached all US users on May 20, 2025 [11], and the two cite different pages more often than not: Ahrefs found only 13.7% of citations overlapped between them [12]. Our guide on how to rank in AI Overviews covers how Google picks those pages.

The looser meaning shows up even in Microsoft's guidance: "Whether you call it GEO, AIO, or SEO, one thing hasn't changed" [5].

How they differ from SEO, and where they overlap

Google states the overlap directly: "The best practices for SEO continue to be relevant because our generative AI features on Google Search are rooted in our core Search ranking and quality systems." [1] Microsoft says the same for Copilot: "Crawlability, metadata, internal linking, and backlinks remain essential" [5].

How much AI Overview citations overlap with organic rankings is disputed. Estimates of AI Overview citations that also rank in the organic top ten run from 16.7% (BrightEdge, 2025) to 76% (Ahrefs, 2025) [17][18]. Every study finds overlap; none agrees on how much.

What Google says you need and don't need

In Google's words:

• "There are no additional requirements to appear in AI Overviews or AI Mode, nor other special optimizations necessary." [19]
• "You don't need to create new machine readable files, AI text files, or markup to appear in these features." [19]
• On llms.txt and similar files: "Doing so will neither harm nor help your site's visibility or rankings in Google Search, as Google Search ignores them." [1]
• On tools: "No third-party tool has access to our internal ranking or AI systems." [1]

Where to start

The full playbook is in our AI search optimization guide, with platform detail in ChatGPT SEO. The groundwork lives in organic SEO and local SEO.

Get the foundations right first

Whatever a vendor calls it, the work that gets a business into AI answers is the same work that gets it onto page one: pages worth citing, accurate profiles and a reputation other sites repeat. Our first page guarantee counts three places, your Google Business Profile in the map results, page one of the organic results, and AI suggestions and answers, and measures the share separately in each of the three places under the written guarantee terms. Start with a free SEO audit, read how the first page guarantee works, or learn more about James Compton.