GEO vs AEO vs AIO vs LLMO: what each means, the full forms, and the difference · Citable
Generative engine optimization (GEO), answer engine optimization (AEO), AI optimization (AIO), LLM optimization (LLMO) and AI SEO: the full form and meaning of each, where the terms came from, and what they have in common.
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written for teams no score out of 100 no ten-step checklist written for teams no score out of 100 no ten-step checklist written for teams no score out of 100 no ten-step checklist
The short version
Term Full form What it is about
GEO Generative engine optimization Being used and cited in answers written by AI — ChatGPT, Perplexity, Gemini, AI Overviews.
AEO Answer engine optimization Being the direct answer to a question — in an AI answer, a featured snippet or a voice assistant.
AIO AI optimization The same idea, named loosely. Also used as shorthand for Google’s AI Overviews, which causes confusion.
LLMO Large language model optimization The same idea, named after the technology instead of the product.
AI SEO AI search engine optimization The umbrella people use when they mean any of the above — or, sometimes, using AI to do ordinary SEO.
What is generative engine optimization (GEO)?
GEO means making your content more likely to be used in an answer that an AI writes. The term comes from a 2023 research paper by researchers at Princeton and IIT Delhi and their collaborators, which tested what made a source more likely to be quoted by a generative engine. What helped, in their tests, was not keyword repetition: it was adding statistics, quotations and citations — giving the engine something specific and attributable to use. Our longer read is generative engine optimization (GEO) .
What is answer engine optimization (AEO)?
AEO is the older word. It was used for featured snippets and voice assistants years before ChatGPT: structure a page so a machine can lift one clean answer out of it. The method has not changed — a question as a heading, the answer in the first sentence, facts as text — only the machines reading it have.
GEO vs AEO: is there a real difference?
A small one. AEO is about being the answer to one question. GEO is about being one of the sources an AI draws on when it writes a longer answer from several pages. In practice the work is the same, and a page that does one well does the other. Anyone selling them as two separate services is selling the same work twice.
What about AIO and LLMO?
They are the same thing again. AIO — AI optimization — is the vaguest of the set, and it collides with “AI Overviews”, the summaries at the top of Google results, so a sentence about “ranking in AIO” can mean either. LLMO — large language model optimization — is the engineer’s name for it. Neither describes work that GEO and AEO do not.
How is any of it different from SEO?
SEO is about where you appear in a list of links. This is about whether you are inside an answer that has no list. Much carries over — a site that is fast, crawlable and trusted is ahead in both. Two things do not:
The readers are different. Googlebot runs your JavaScript. Most AI crawlers do not, so a price drawn by a script exists for Google and not for ChatGPT. The names of those crawlers are in the AI crawler list .
There is no position two. An answer names a few sources or it does not. You are not ranked lower; you are absent.
What all five have in common
Whatever it is called, the work is four steps, and they happen in this order:
Access — the engine’s crawlers are allowed in, by robots.txt and by whatever sits in front of the site.
Comprehension — the facts are in the HTML as text, not behind a script, and not buried under the theme.
Trust — the page is specific, attributable and consistent with what is said about you elsewhere.
Choice — the model decides. This step belongs to it, whatever anyone sells you.
The acronym does not matter. A page that cannot be reached or cannot be read is out at step one or two, long before anything called GEO or AEO applies to it.
Where to start
Start at the bottom of the chain, because it is the part you fully control and the part most sites fail. The free scan fetches one of your pages the way an AI crawler does and shows what it was given. Citable then handles access and comprehension for you — every AI crawler is served the content alone, at the same address, while people and Google get the page as it is — and shows you which engine read which page. The full treatments are generative engine optimization and answer engine optimization , and the practical version is how to get cited by ChatGPT .
The chain, drawn Access, then comprehension, then the choice.
Access — an engine you refuse never reads anything.
Comprehension — the facts have to survive the markup.
Choice — which stays the model’s, whatever anyone sells you.
Read next The rest of the set.
6 min read AI search optimization
How an assistant decides what to say about your site, and which of those steps a team can actually influence.
7 min read What GEO can and cannot do
What generative engine optimisation means, what it borrowed from SEO, and which parts of it are sold as certainty but aren't.
5 min read How AI crawlers read a website
Rendering, fetch budgets, robots.txt, and why a JavaScript-drawn price is invisible to almost every engine reading you.
8 min read Generative engine optimization (GEO)
What it means, how an AI engine chooses its sources, the strategies with evidence behind them, and what GEO tools actually do.
7 min read Answer engine optimization (AEO)
What it means, three before-and-after examples, the practices that matter — and the step that comes before any of them.
6 min read How to get cited by ChatGPT
How ChatGPT picks the pages it cites, and the six things a site can actually do to show up in its answers.
5 min read Can ChatGPT read my website?
How it reads a site, why it does not run JavaScript, the five things that stop it, and how to check in a minute.
5 min read llms.txt: what it is, and what it does not do
What goes in the file, a working example, best practices — and whether any AI search engine actually reads it.
5 min read utm_source=chatgpt.com, and tracking AI traffic in GA4
What the tag on your URLs means, why ChatGPT adds it, and how to see every AI engine in Google Analytics.
6 min read Should you block AI crawlers?
Training bots, search bots and live fetch are three different decisions — and the one blocked by accident costs the most.
Or just look at it One page, served both ways.
What survives each trip, with the token count for both.
About Citable Who is behind this page, and what we stand on.
When an AI agent — ChatGPT, Claude, Perplexity or any of the 81 that Citable recognises — opens a page, Citable removes the theme, scripts, navigation and layout and serves only the content: the same facts, at the same URL, on the site's own domain. People and Google still get the full designed page.
Who opens the page What they are given
A person in a browser The full designed page, untouched.
Googlebot, Bingbot and other search engines The full designed page, untouched.
An AI agent — GPTBot, ChatGPT-User, ClaudeBot, PerplexityBot and the rest The content only: no UI, no scripts, the same facts at the same URL.
Measured, not estimated. A real product page of 386.8 KB is served to AI agents as 4.6 KB — 98.8% smaller, with the same facts. Every figure on this site comes from a fetch anybody can repeat.
One list. The 81 AI agents named on these pages are the list the product itself runs on. A page here cannot describe a crawler Citable does not serve.
Search is never touched. Googlebot and Bingbot always get your real page. The clean copy is for AI agents only — at the same address, with the same facts.
Checked, not trusted. A user agent is a claim, and anyone can send one. Where an operator publishes its addresses, every read is checked against them and recorded as verified or not.
Nothing about your visitors. Citable sees which crawler read which page. It does not see who your customers are, and their details never reach us.
Honest about limits. Nobody can promise a citation or a ranking, and we do not. What we show is what an AI agent was given, and whether it sent somebody back.
How it works · The measurements · What it touches and stores · Why Citable · Pricing · Questions, answered plainly · Talk to us
Free · about 20 seconds · no signup Find out whether AI has ever read your site.
Type your address. We fetch a page exactly as GPTBot does, count the tokens, and score fifteen things an answer engine needs. If the log then stays empty for a month, that is worth knowing too.
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