SEO vs AEO vs GEO: What's the Difference — and Where AX Fits
SEO gets your page found in search results. AEO gets it used as a direct answer. GEO gets it cited inside AI-generated answers. AX (agent experience) decides whether an AI agent can actually fetch and read your page when it checks you out.
The four are layers, not replacements. New research from 2026 suggests the last layer now matters most: across 37,927 AI agent journeys, businesses with agent-readable sites were clearly recommended 1.9x more often than comparable businesses without them.
What is SEO?
Search engine optimization (SEO) is the practice of making a page eligible and competitive in a ranked list of search results. Success means a high position and a click.
SEO covers crawlability, indexing, relevance to the query, page quality and authority signals such as links. It is still the foundation for everything below: Google states that appearing in AI Overviews and AI Mode requires no special optimization beyond normal SEO best practice, and that a page must be indexed and eligible for a snippet to be shown there.
What is AEO?
Answer engine optimization (AEO) is the practice of structuring content so a system can lift a short, direct answer from it. The classic targets were featured snippets and voice assistants; today the term is also used for AI answers in general.
Success means your page supplies the answer, often without a click. Typical tactics are question-style headings, a concise answer right under the heading, and clean structured data.
Recently, AEO advice has also moved off-site: seed mentions in forum threads, listicles and review sites so AI engines are more likely to surface you. As the next sections show, the evidence for that off-site layer is weaker than the advice suggests.
What is GEO?
Generative engine optimization (GEO) is the practice of making content more likely to be selected and cited when an AI system writes a synthesized answer from several sources. The term comes from Aggarwal et al., presented at KDD 2024, who reported visibility gains of up to about 40% from edits such as adding citations, quotations and statistics.
Success means being cited or recommended inside the answer, not ranking first in a list.
Two caveats matter. First, those gains were measured in a controlled benchmark where the source was already among the documents given to the model. Second, a 2026 e-commerce study from MIT and Columbia (E-GEO) found that many popular GEO heuristics backfire: an advertising or assertive tone pushed products down, and longer text had no effect at all. What helped was plain, factual, well-structured content.
What is AX, and why does it matter now?
Agent experience (AX) is how easily an AI agent can fetch and read your own site. It matters because modern AI assistants no longer answer from memory alone: they search, open the results and read them before they recommend anything.
That is the core argument of AX is the New AEO (Finder, Elovic, Shalev and Yosef, 2026). One buyer question can send an agent through several rounds of search and fetch. Being surfaced gets you onto the shortlist; being readable decides what the agent says about you.
What the study measured
The authors ran 37,927 agent journeys, each a buyer question about a real business, across four independent agent setups and 1,056 businesses. Businesses were matched on fame, prior model knowledge and two AEO proxies, then split by how agent-ready their sites were.
What it found
A note on the source
This is a 2026 preprint and has not yet been peer reviewed. The authors work at ora, whose own ranker is used to score agent-readiness; they disclose this and release their code. They also note that content depth was not matched between groups, so thinner content may explain part of the difference.
How do SEO, AEO, GEO and AX fit together?
Think of them as steps in one journey: your page must be found, then read, then chosen. Each discipline covers a different step, and each depends on the one before it.
| Discipline | Step | Goal | Success looks like | Main lever |
|---|---|---|---|---|
| SEO | Found | Rank in search results | Position and clicks | Crawlability, relevance, authority |
| AEO | Found / chosen | Supply a direct answer | Snippet or answer inclusion | Question headings, concise answers, structured data |
| GEO | Chosen | Be cited in AI answers | Citation or recommendation | Clear, factual, well-structured content |
| AX | Read | Let agents fetch and read your site | Answers built from your own pages | Server-rendered content, open access for agents, machine-readable structure |
The practical consequence: GEO and AEO tactics only pay off if an agent can actually read the page. A site that is widely talked about but hard to fetch hands the description of your business to someone else's pages.
What should you do first?
Start with readability, then clarity. Off-site tactics come last, because the evidence for them is weakest.
Want to see how your page scores on these signals? Run it through the free Horus Index GEO Visibility Checker. It is rule-based and deterministic, so the same page gets the same score every time.
Frequently asked questions
Is GEO replacing SEO?
No. AI search still draws on pages that search systems can find and index. GEO and AX add layers on top of SEO; they do not remove the need for it.
Is AEO the same as GEO?
They overlap and the terms are often used interchangeably. AEO traditionally targets single direct answers such as featured snippets and voice results. GEO targets synthesized answers built from several sources.
Do I need an llms.txt file?
It is optional. Google says no special AI text files are needed for its AI features, and the AX study found that only about one in three agents that read an llms.txt file went on to fetch a page it listed.
Does longer content get cited more?
Not on its own. In the E-GEO study, changes in text length had no measurable effect on how AI systems ranked products. Clear structure and factual wording mattered more.
Can I track AI visibility in Google Search Console?
Partly. Since August 2026, Search Console has a report showing impressions in AI Overviews and AI Mode. It does not include click data.