Search is no longer a single discipline.

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As AI systems increasingly sit between buyers and sellers, four overlapping optimisation models now exist:

• SEO (Search Engine Optimisation)

• AEO (Answer Engine Optimisation)

• GEO (Generative Engine Optimisation)

• AIO (AI Optimisation)

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They are related — but they are not interchangeable.

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Understanding the difference is critical. Confusion here is one of the main reasons businesses invest in “AI search” initiatives and see no results.

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This article explains what each discipline actually does, what it optimises for, and how they fit together in 2026.

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For the full strategic framework, see our pillar guide:

SEO & GEO in 2026: The Complete Guide to Winning AI-Driven Search

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SEO (Search Engine Optimisation): Getting Indexed and Found

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SEO optimises for discoverability.

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Its job is to help search engines:

• Crawl your site

• Index your content

• Rank pages for relevant queries

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SEO answers the question:

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“Can this page be found when someone searches?”

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What SEO optimises

• Keywords and search intent alignment

• Site architecture and internal linking

• Technical performance (Core Web Vitals, crawlability)

• Backlinks and authority signals

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What SEO produces

• Rankings

• Organic traffic

• Visibility in traditional SERPs

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SEO is still foundational.

But it is no longer sufficient on its own.

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AEO (Answer Engine Optimisation): Appearing in Direct Answers

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AEO optimises for answers, not pages.

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It focuses on helping systems like Google, Bing, and voice assistants extract direct responses from your content.

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AEO answers the question:

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“Can this content be used as a direct answer?”

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What AEO optimises

• Clear question-and-answer formatting

• Structured content (FAQs, definitions, summaries)

• Schema markup

• Concise, extractable explanations

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What AEO produces

• Featured snippets

• “People also ask” results

• Voice search answers

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AEO improves answer visibility, but it does not determine who gets recommended.

GEO (Generative Engine Optimisation): Being Selected and Recommended

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GEO optimises for trust, reasoning, and citation.

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It is designed for AI systems that:

• Synthesize multiple sources

• Evaluate credibility

• Generate a single response or short list of recommendations

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GEO answers the question:

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“Is this a reliable source to cite or recommend?”

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What GEO optimises

• Entity clarity (who you are, what you do)

• Topical depth and first-principles explanations

• Consistency across content and platforms

• Verification and authority signals

• Explanatory quality (teaching, not marketing)

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What GEO produces

• AI recommendations

• Citations in generative responses

• Inclusion in AI decision outputs

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This is the layer where AI trust is built.

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If an AI system cannot confidently explain why you are credible, you will not be selected — regardless of rankings.

AIO (AI Optimisation): The Umbrella Term (And Why It’s Often Misused)

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AIO is not a discipline. It is a catch-all.

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In practice, AIO is used to describe:

• SEO + AEO + GEO combined

• Or any attempt to “optimise for AI” without specificity

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This creates confusion.

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Without defining which AI behaviour you are optimising for — retrieval, answering, or recommendation — AIO strategies tend to fail.

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AIO only works when it is grounded in:

• SEO for discovery

• AEO for answers

• GEO for selection and trust

How These Disciplines Fit Together

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The simplest way to understand the stack:

• SEO helps you get found

• AEO helps you appear in answers

• GEO helps you get recommended

• AIO is the combination — when done intentionally

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Or put another way:

This distinction is explored in depth in our pillar article on SEO & GEO in 2026, where we show how AI systems actually reason across these layers.

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Why This Distinction Matters in 2026

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Search is no longer just retrieval.

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AI systems are increasingly:

• Filter options before users see them

• Explain decisions on behalf of users

• Recommend providers directly

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That shifts the competitive question from:

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“Who ranks?”

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to:

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“Who is trusted to explain and recommend?”

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SEO brings you into the conversation.

GEO determines whether you are chosen.

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Final Thoughts

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Most businesses think they are “doing AI optimisation”.

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In reality, they are:

• Still doing SEO

• Occasionally doing AEO

• Not doing GEO at all

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That gap is where AI-driven growth is being won and lost.

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If you want to understand how these disciplines work together as a system — not isolated tactics — start with the pillar guide:

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SEO & GEO in 2026: The Complete Guide to Winning AI-Driven Search

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