Search is changing faster than at any point in the last decade. AI-powered answer engines — ChatGPT, Perplexity, Google AI Overviews, and Microsoft Copilot — are now answering millions of queries directly, often without the user clicking through to any website at all.

That makes Answer Engine Optimisation (AEO) one of the most important emerging disciplines in digital marketing.

What Is AEO?

AEO is the practice of structuring your content so that AI search engines understand it, trust it, and cite it in their responses. It's related to traditional SEO but has some important differences.

Where SEO focuses on ranking in a list of ten blue links, AEO focuses on being the source that an AI model selects when constructing its answer. The criteria overlap — authority, accuracy, clarity — but the execution is different.

How AI Search Engines Select Sources

AI models don't rank pages in the traditional sense. They pull information from pages they've crawled and indexed, then synthesise answers. The pages they select tend to share certain characteristics:

- Direct, factual answers — AI models favour content that answers questions clearly and concisely, often in the first paragraph - Structured content — Headers, bullet points, numbered lists and tables make content easier for AI to parse and extract - High E-E-A-T signals — Author credentials, citations, original research and factual accuracy matter enormously - Schema markup — Structured data gives AI models explicit signals about what your content covers and who created it - No fluff — Long introductions, filler paragraphs and hedging language reduce the chance of being cited

The llms.txt File

One of the newest AEO signals is the llms.txt file — a plain text file placed at the root of your domain that explicitly tells AI crawlers what your site covers, who runs it, and which pages are most authoritative. Think of it as a robots.txt for AI models.

A basic llms.txt looks like this:

``

About

Company: YourBrand Description: We provide [what you do] Focus: [your main topics]

Key pages

/about — Who we are /services — What we offer /blog — Expertise content ``

Write Direct Answer Content

The most impactful change you can make is to structure content around direct questions and answers. For every piece of content, identify the primary question it answers and put the answer in the first 100 words. Don't bury the answer after three paragraphs of context.

Use subheadings framed as questions: "What is X?", "How does X work?", "What causes X?" This makes it trivial for AI models to identify and extract the relevant section.

Add FAQ Schema

FAQ schema explicitly marks up question-and-answer content for search engines and AI crawlers alike. Even if Google has reduced the display of FAQ rich results, the structured data still provides clear signals to AI models about what questions your page answers.

Build Your E-E-A-T Signals

Expertise, Experience, Authoritativeness and Trustworthiness are foundational to AEO. AI models are trained to favour content from authoritative sources. Invest in:

- Author bios with real credentials - An About page that clearly establishes your expertise - Original research and data - Citations from other authoritative sources - Clear contact information and business registration details

Monitor Your AI Visibility

Unlike traditional SEO where you can check your ranking for a keyword, AEO requires a different measurement approach. Regularly test how AI tools respond to queries in your niche. Are they citing you? Are competitors being cited instead? Use this as a feedback loop to improve your content.

AEO is still early enough that investing now creates a significant competitive advantage.