Glossary
Four of these describe roughly the same work: making a site the thing an AI names when someone asks a question. They were coined at different times, by different people, for different surfaces, and nobody has ever agreed on how they nest. If you only have five minutes, skip the vocabulary and run the one check that decides all of it — whether your robots.txt is blocking the crawler in the first place.
If you have longer: below is each term, who coined it and when, and when it is worth using. Then the part almost nobody prices honestly — which half of the premium buys work that did not exist before, and which half buys the same five checks under a newer name.
The glossary
Coined: in use since the late 1990s. Means: optimizing to appear in a ranked list of links. Use it when: the target is position in a results page. Everything below inherits its technical foundation — crawlability, structure, credible content — which is why a site that fails at SEO fails at all of them at once.
Coined: by Jason Barnard of Kalicube, published in a Trustpilot white paper in January 2018 and presented at BrightonSEO that April. Means: optimizing for surfaces that return one answer instead of ten links. Note the date: this is a pre-generative term, built for featured snippets and voice assistants — Siri, Alexa, Google Assistant. It was stretched later to cover AI assistants because the underlying problem turned out to be identical. Use it when: your concern genuinely includes snippets, People Also Ask and voice, which have not disappeared.
Coined: Aggarwal, Murahari, Rajpurohit, Kalyan, Narasimhan and Deshpande, in a paper published November 2023 and presented at ACM SIGKDD 2024. Means: optimizing for inclusion in a synthesized answer, where there is no list and often no click. Why it is the defensible one: it is the only term here with a peer-reviewed origin, a benchmark (GEO-bench) and a definition someone can check. The paper reported visibility gains of up to 40% in generative responses, and found that adding statistics, quotations and cited sources worked — while keyword stuffing, the classic SEO reflex, performed poorly and sometimes negatively.
Coined: no moment, no paper. It surfaced across vendor blog posts through 2024 and 2025 as ChatGPT became the engine people worried about by default. Means: in practice, what GEO means. The distinction it claims: emphasis on the model rather than the engine. Use it when: your audience already uses the word. It carries no definition you can hold anyone to.
This is where the ground genuinely gives way. One body of writing uses AIO for optimizing content for AI systems. Another uses it for applying AI to analyze data and improve content performance — optimizing with AI. Those are not variations on a theme; they are opposite directions of the same arrow, sharing three letters. Use it when: never, without asking which one is meant. If a proposal quotes you for AIO, that question should come before the number does.
It gets listed alongside these four often enough to be worth stating plainly: /llms.txt is a file, proposed for telling AI crawlers what a site is and which pages matter. Its status as a standard remains unconfirmed. It belongs in a checklist, not in a taxonomy of disciplines.
Nobody knows, and the disagreement is on the record. Four sources published within roughly a year of each other, each placing a different acronym at the top of the tree:
These cannot all be true. There is no standards body here, no RFC, no governing definition — just vendors, each with a commercial reason to place their preferred acronym at the top. The most candid statement on the record comes from a directory of AEO and GEO agencies, which notes that most agencies now use the terms interchangeably, that the underlying work overlaps almost completely, and that buyers say AIO, AI SEO and LLMO to express the same purchase intent. That is a directory of the vendors selling the premium, saying the labels are the same product.
The reason the acronym matters less than the check: of 67 domains this pipeline flagged as blocking an AI crawler in robots.txt, only 15 were blocking one that affects live citation. The other 52 block training collectors only — CCBot, Bytespider, Google-Extended — which does not stop ChatGPT or Perplexity from citing the site at all.
That distinction is invisible in every acronym on this page, and it changes the diagnosis completely. A vendor telling all 67 of those companies that AI cannot cite them would be wrong about 52 of them. The letters on the proposal do not catch that. Reading the robots.txt does.
Use GEO when you need a defensible term. It has a paper behind it, a benchmark, and a definition someone can check.
Use AEO if your concern includes featured snippets, People Also Ask and voice — surfaces that predate generative AI and still drive volume.
Treat LLMO and AIO as marketing vocabulary. Not dishonest, but not load-bearing. If a vendor's differentiation rests on which of the four they use, the differentiation is the acronym.
And when a proposal arrives, ignore the letters on the cover. Ask two questions instead: what will you change on my site, and what will you do off it. The answers price the work. The acronym prices nothing.
Questions
No, but the overlap is large. The technical foundation — crawlable pages, clear structure, credible content — is shared. What differs is the target: SEO optimizes for position in a list, GEO for inclusion in a synthesized answer where there is no list and often no click. The published research found the tactics diverge too, with keyword stuffing actively hurting generative visibility.
Yes, if used precisely. AEO was built for single-answer surfaces, and featured snippets and voice assistants have not disappeared. Used loosely as a synonym for GEO, it means nothing in particular.
Only against a scope you can inspect. If the added work is schema and a few rewritten pages, the premium is not justified — that is a fixed-scope project, not a retainer. If it includes off-site citation building and multi-engine monitoring, the premium reflects real cost.
GEO, for the reason given above: it is the only one with a checkable definition. The work itself is five specific checks run against live pages, and the name matters less than the findings.
Send the domain. You'll get the findings back either way — no acronym required.
Ask for a free look at your siteSources
Hierarchy claims above are attributed to published pages by Salesforce, Pepper Content, TurboAudit and Contently, quoted as evidence of the disagreement rather than as authority.
Cite this
Four acronyms describe roughly the same work, and the industry has never agreed on how they nest — you can find four reputable sources each naming a different one as the umbrella term. The price premium is real for the off-site work almost nobody sells, and inflated for the on-site work everybody sells.
Igor Almeida, Rankavex. Last updated 2026-09-05https://rankavex.com/ai-search-acronyms/