What Is Answer Engine Optimization?

Answer engine optimization (AEO) is the practice of writing and structuring your content so that AI systems — ChatGPT, Perplexity, Gemini, Google's AI Overviews — quote it directly when someone asks a question your business can answer. Where traditional SEO competes for a position in a list of links, AEO competes to be the sentence the machine repeats.

It is a narrower, more specific job than it sounds, and unlike most of what gets sold under the AI-search banner, there is real published research on what works. If you want the wider picture first, start with what AI SEO actually is.

The short version

• AEO is about being quoted. Generative engine optimization (GEO) is about being included. They are two halves of one job and no serious agency should sell them separately.

• Ranking well on Google does not get you cited by AI assistants. Ahrefs found only 12% of URLs cited by ChatGPT, Gemini and Copilot appear in Google's top 10 for the same prompt.

• The Princeton and IIT Delhi research tested nine tactics. Citing sources, adding statistics and writing fluently worked. Keyword stuffing actively made things worse.

• Schema markup is not on the list of things shown to work, despite being one of the most commonly sold AEO deliverables.

What is an "answer engine", exactly?

An answer engine is any system that responds to a question with a composed answer rather than a list of places to look. ChatGPT is one. Perplexity is one. Google's AI Overview is one bolted onto a traditional search engine.

The behavioural shift matters more than the terminology. When someone searches, they are browsing. When someone asks, they are expecting to be told. The second posture is far less likely to end in a click, and far more likely to end in a decision made on the strength of whatever the system said.

AEO is the work of making sure that what it said includes you, accurately.

How is AEO different from SEO, and from GEO?

Three terms, one underlying job, worth separating precisely because vendors blur them.

SEO earns a position in a ranked list. Success is measurable in positions and clicks.

GEO — generative engine optimization — earns inclusion in a generated summary. The system is surveying a topic and deciding which businesses merit naming. You want to be named.

AEO — answer engine optimization — earns direct quotation. The system needs a specific sentence to answer a specific question. You want it to be your sentence.

In practice GEO and AEO pull on the same levers and we treat them as one service, not two. If a proposal prices them as separate line items, that is a packaging decision, not a technical one.

The honest distinction from SEO is not the tactics — it is the feedback loop. SEO tells you where you stand every day. AEO tells you almost nothing unless you deliberately go and look.

Does ranking on Google get you cited by AI?

Mostly no, and this is the finding that should reset expectations.

Ahrefs analysed 15,000 long-tail prompts across ChatGPT, Gemini, Copilot and Perplexity (Louise Linehan, August 2025). On average, only 12% of the URLs those assistants cited appeared in Google's top 10 results for the same prompt.

Perplexity was the exception — close to one in three of its citations pointed at pages ranking in Google's top 10, which suggests its retrieval is more closely aligned with Google's own ranking logic than its competitors' are.

Sit with the 12% for a moment. It means that for the three most-used assistants, the overlap between "wins on Google" and "gets quoted by AI" is small. A business ranking beautifully can be invisible in AI answers. A business that has never cracked page one can be cited routinely.

That cuts both ways, and for a smaller business the second direction is the interesting one. Being outranked on Google by competitors with twenty years of link equity does not automatically mean being out-cited in an answer engine. It is a different contest, scored differently.

What it does not mean is that SEO no longer matters. A page that cannot be crawled cannot be cited, and Google's own AI Overviews draw more heavily on ranked pages than external assistants do. The correct reading is that ranking is necessary groundwork and nowhere near sufficient.

What actually works? The research

This is the part of AEO with genuine evidence behind it, and it is worth knowing in detail because it is so often misrepresented.

Researchers from Princeton University and IIT Delhi (Aggarwal, Murahari, Rajpurohit, Kalyan, Narasimhan and Deshpande) built GEO-bench, a benchmark of 10,000 queries across 25 domains, and tested nine different ways of rewriting a page to see which made a generative engine more likely to feature it. The headline: the best methods lifted visibility by up to 40%.

The nine methods tested were: authoritative tone, adding statistics, keyword stuffing, citing sources, adding quotations, simplifying language, improving fluency, using unique words, and adding technical terms.

What performed best:

• Citing sources — attributing claims to named, credible origins

• Adding quotations — including direct quotes from relevant authorities

• Fluency optimization — simply writing more clearly

Those three landed around a 27–28% improvement on the paper's position-adjusted visibility metric, against a baseline of 19.3.

What backfired:

Keyword stuffing made things worse. It dropped the same metric from 19.3 to 17.7 — the researchers filed it under non-performing methods. The tactic that defined a decade of bad SEO is not merely ineffective on answer engines; it is counterproductive.

Two caveats you should hold onto. The authors themselves found that effectiveness varied by domain, and said so: the paper calls for domain-specific optimization rather than one universal recipe. And this is benchmark research, not a measurement of live production systems — a controlled result, which is exactly what makes it credible and also what limits how literally you should read the 40%.

The thing this paper is constantly misquoted about

You will see the Princeton study cited as proof that schema markup improves AI citation. It tested nine methods and schema was not one of them. Structured data does not appear in the paper at all.

That misattribution matters because "semantic schema built for LLMs" is one of the most commonly sold AEO deliverables. The independent evidence for it is thin: a Search Atlas study found no correlation, and Google's John Mueller — speaking personally in January 2026 — summarised the position as "yes, no, and it depends." The only first-party confirmation came from Bing, and it was narrow and specific.

Schema is still worth having. It helps machines read your prices, hours and addresses without guessing, and that is a real benefit. It is simply not the AEO lever it is sold as, and a proposal built around it is a proposal built on the weakest evidence in the category.

So how do you write a page an answer engine will quote?

Everything below follows directly from the research above.

Answer the question in the first two sentences. If a system is scanning for a quotable answer, it should not have to excavate one from paragraph six. Say the thing, then explain it.

Attribute your claims. "Ahrefs found X, in a study of 15,000 prompts" is more quotable than "studies show X", because the first is a self-contained, verifiable sentence and the second is not. This is the single clearest finding in the research.

Use real numbers, and put them in the sentence. "Only 12% of AI citations come from Google's top 10" survives extraction. "Very few AI citations come from top-ranked pages" does not.

Write one idea per section. A section that can be lifted out and still make sense is a section that can be quoted. A section that depends on three paragraphs of preceding context cannot.

Make your headings the questions people actually ask. Not keyword fragments — questions, phrased the way a person would type or speak them.

Write clearly. The plainest finding in the paper is also the least glamorous: fluency improvement was among the top performers. Clear prose wins.

And stop stuffing keywords. It is measurably worse than doing nothing.

None of that is a trick. It is the description of a genuinely useful page, which is roughly what you would expect the systems to be selecting for.

How do you measure AEO?

Badly, if you wait for your analytics to tell you. A quoted answer often produces no click, no session and no referrer. The event that mattered leaves no trace in GA4.

The workable method is manual and cheap:

Fix a list of 15 questions. The real ones — what a buyer would ask before choosing someone in your category. Write them down once and do not change them, because the entire value is in comparing like with like over time.

Run them monthly, across ChatGPT, Perplexity, Gemini and Google, on the same day each month.

Record three things: were you named, was your site cited, and who else was named. That third column is the one people skip and the one that turns the log into competitive intelligence.

Within three or four months, that log tells you whether anything you are doing is working. It costs an hour a month. We published what that test turned up across eight US markets in one industry, if you want to see what the output looks like. If you buy a monitoring tool later, you will know what its numbers should look like — which is a much better position than taking a dashboard's word for it.

Not sure whether AI systems are naming you or your competitors?

That is the first thing we check. Our written audit runs the prompts for your category, records who gets named and cited, and lays out the gaps in priority order. It's free, and you get a document rather than a sales call.

Get a free SEO and AI visibility audit →