GEO, AEO, AISEO, LLMO: what each AI search optimization term actually means

The six terms you'll see

The acronym soup in this space exists because four things happened at once. AI answer engines emerged. The SEO industry needed a name for the new work. Several practitioners and vendors coined different terms more or less simultaneously. None of them have an authoritative governing body to settle on one. So we ended up with six.

Here is what each one actually refers to, in plain language.

SEO — Search Engine Optimization

The original. Coined in the late 1990s, it describes the work of making content findable and rankable in traditional search engines like Google and Bing. It encompasses on-page optimization, technical site health, link building, content quality, and entity signals.

Some commentators have written SEO's obituary in 2025, which is premature. Every AI answer engine still uses retrieval — they search the web, find sources, and synthesize answers. The retrieval layer is still SEO. In our reference dataset, SEO authority correlates with AI visibility at r = 0.89, meaning roughly 79% of the variance in how often a brand gets cited by ChatGPT, Claude, Gemini, and Perplexity is explained by its SEO authority.

SEO didn't get replaced. It became the foundation that every other term in this list builds on.

GEO — Generative Engine Optimization

The term that won 2025–2026. GEO entered the conversation through an academic paper — Aggarwal et al., "GEO: Generative Engine Optimization" — and was rapidly adopted by the SEO industry as the cleanest label for "make your brand citeable inside AI-generated answers."

GEO specifically refers to optimization for generative answer engines: ChatGPT, Claude, Gemini, Perplexity, and Google's AI Overviews. The work involves making your content easy to ingest, understand, attribute, and cite during the engine's generation process. It overlaps heavily with SEO but adds discipline-specific tactics: structured data that helps machines verify your claims, citation-worthy formatting, entity disambiguation, and visibility across the actual training and retrieval corpora these engines use.

If you're going to use one term, GEO is the most common as of 2026.

AEO — Answer Engine Optimization

AEO predates the LLM era. It was coined around 2018–2020 to describe the work of optimizing for "answer engines" — voice assistants like Alexa and Siri, Google's featured snippets and Knowledge Panels, and direct-answer surfaces that bypassed the traditional ten-blue-links result page.

When generative AI arrived, some practitioners adopted AEO for the new work because the underlying job was the same: get your content surfaced as the answer, not just as a result the user has to click through and read. AEO is therefore the broader term — it includes voice search, featured snippets, AI Overviews, and LLM citations all under one umbrella.

If you want one term that covers every "answer surface" Google and others have created over the last seven years, AEO is the better fit. If you specifically mean LLM answer engines, GEO is more precise.

AISEO and AI SEO

AISEO is the informal, generic term. It tends to be used by people who find GEO and AEO unnecessarily jargony, or by content marketers who want a term their CMO will immediately understand without explanation. AI SEO is the same thing with a space.

AISEO doesn't have a precise definition — it can mean GEO, AEO, or "anything SEO-adjacent involving AI" depending on who's using it. That's both its strength (accessible) and its weakness (imprecise). It works fine in casual conversation; it works less well in scopes of work or service contracts.

LLMO and LLM SEO

LLMO — sometimes written LLM SEO or LLM Optimization — is the term preferred by practitioners who feel GEO is too imprecise. Their argument: "generative engine" is fuzzy, because Google's AI Overviews are partly retrieval and partly generation. LLMO restricts the scope to actual LLM-produced text — ChatGPT, Claude, Gemini, Perplexity — and leaves AI Overviews in a separate bucket.

It's a defensible distinction, but most of the industry hasn't followed it. LLMO has weaker adoption than GEO. If you use it, expect to spend the first paragraph of every conversation explaining what you mean.

The fringe terms

You'll occasionally see:

• SGO — Search Generative Optimization. Mostly used by people who want to differentiate from "generative engines" as a category.
• GAIO — Generative AI Optimization. Slightly broader than GEO; sometimes includes optimization of internal AI tools, not just public answer engines.
• AIO — AI Optimization. Ambiguous — sometimes means AI Overview Optimization, sometimes a generic catch-all.
• GSEO — Generative SEO. Rarely seen but occasionally appears.

None of these have meaningful industry adoption. If you encounter them, the speaker means roughly the same thing as GEO or AEO. Don't waste time arguing terminology.

Side-by-side comparison

What's actually different between them

Strip out the marketing layer and three real distinctions remain. Worth understanding because they affect vendor selection and scope of work.

1. Whether voice and featured snippets are in scope

This is the cleanest split. AEO includes voice and traditional-search direct-answer surfaces. GEO and LLMO don't. If your brand has a real voice search use case (smart speakers, in-car assistants, home automation), AEO is the more accurate label for the work you need.

For most B2B brands, voice is irrelevant. So the AEO–GEO distinction collapses to GEO being the more precise term for the actual work being scoped.

2. Whether AI Overviews are in scope

Google AI Overviews are a hybrid. They use retrieval (like SEO) and they generate text (like GEO). LLMO purists exclude them on the grounds that they're not pure LLM output. GEO practitioners include them, because the optimization work is mostly the same.

For most marketing leaders, AI Overviews matter — they're appearing in increasing percentages of Google search results. Excluding them on terminology grounds is academic. We include them in GEO scope.

3. Whether the underlying SEO foundation is part of the brief

This is the most important distinction in practice, and it's not really about the acronym. Some agencies sell GEO as a bolt-on to existing SEO work. Others sell it as a discipline that requires SEO foundations to be in good shape first. The second framing is more honest, given that SEO authority correlates with AI visibility at r = 0.89.

Whichever term you pick, get the answer to "is SEO foundation work included or assumed?" in writing. Because if it's assumed and your foundations are weak, the GEO work won't move the numbers.

What's the same — most of it

Once you set aside the three real distinctions above, the work behind every term in this list is largely shared. To rank in Google, get cited by ChatGPT, surface in AI Overviews, or appear in Perplexity citations, you need the same things:

• Authoritative content — depth, accuracy, original perspective, clear authorship.
• Strong entity signals — schema markup, consistent NAP across the web, clear "this is who we are" disambiguation.
• Citation-worthy mentions — your brand appearing in places engines treat as credible: industry media, Wikipedia, peer-reviewed sources, well-ranked competitor content that mentions you.
• Clean technical fundamentals — crawlability, indexability, site speed, structured data correctness, accessibility.
• Topical depth — covering a subject area comprehensively rather than producing isolated pieces.

An SEO from 2018 brought into a 2026 GEO meeting would recognize 80% of the agenda. The deltas are real but bounded.

Which term should you use?

Practical guidance, by context.

For internal team conversations

Pick one and stay consistent. The cost of switching between GEO, AEO, and AISEO mid-document is more confusion than the precision gain. We use GEO at visible.md because it's the term most of our clients arrive having heard. If your organization already has people using AEO, stick with AEO.

For public-facing content and SEO

GEO has the search volume and won the Google ranking battle in 2025–2026. If you're writing content to be discovered, GEO is the term to lead with. Mention the others as synonyms in passing — readers searching for AEO or AISEO should still find your piece.

For job titles and hiring

Use what your industry uses. In ecommerce and content marketing circles, GEO is winning. In voice-search-heavy spaces (automotive, smart home, hospitality), AEO is still preferred. If you're hiring, the term affects the candidate pool — AEO will surface candidates with five-plus years of voice-search experience; GEO will surface candidates with 18 months of LLM-era practice.

For scopes of work and contracts

Use whichever term feels natural, but always define the scope explicitly. "GEO services" without specification could mean anything from prompt analysis to full execution. The acronym carries less meaning than the deliverables list. Specify which engines, which deliverables, what cadence, and whether SEO foundation work is included.

What we use, and why

At visible.md we use GEO. Two reasons. First, it's where most of our prospects arrive — they've heard "GEO" in a board meeting or on a podcast and that's what they search for. Second, GEO has the cleanest definition: optimization for LLM-powered answer engines plus the hybrid surfaces (AI Overviews) that behave like them.

That said, we don't pretend GEO is a separate discipline from SEO. Our audits triangulate AI visibility across five engines (ChatGPT, Claude, Gemini, Perplexity, Google AI Overviews) and SEO authority across four data providers (Ahrefs, Semrush, Moz, DataForSEO) — because the strongest predictor of how often your brand gets cited in AI answers is still your SEO authority. The two halves are part of the same problem, and we measure them together. Whatever you call the work, the data has to come from both.

The closing point

Most of the time when someone asks "should we be doing GEO or AEO or AISEO?" the most useful answer is: the work is mostly the same, pick one term that fits your audience, and get on with the work. The brands that are winning citations in ChatGPT and Claude and Gemini in 2026 aren't the ones who picked the right acronym. They're the ones who built strong SEO foundations, produced citation-worthy content with clear authorship, made themselves easy to verify and disambiguate, and measured the result across multiple engines.

The acronym is a label on a job. The job hasn't changed nearly as much as the labels suggest.