What is generative engine optimisation (GEO)? The plain-English guide.

What GEO actually is

Generative engine optimisation, GEO, is the practice of making a brand easy for AI assistants to understand, trust and quote. It covers ChatGPT, Gemini, Perplexity, Copilot and Google’s AI Overviews, and it optimises for being cited inside a synthesised answer rather than ranked in a list of links.

You will also hear it called answer engine optimisation or AI SEO. The labels vary; the work is the same. When someone asks an assistant “who should I use for X” or “what does Y cost”, the assistant picks a handful of sources and states an answer. GEO is the discipline of being one of those sources, consistently, for the questions your buyers actually ask.

It matters because of simple arithmetic. A results page has ten slots and years of accumulated habit behind it. An AI answer has three or four citations and a user who often never clicks anything else. Fewer slots, higher stakes, and a completely different set of reasons for who gets picked.

GEO vs SEO: same foundations, different finish line

The honest answer is that GEO is mostly SEO done well, plus a different idea of what winning looks like. Crawlability, site structure, content quality and authority still do the heavy lifting, because most assistants either search the web live or lean on a search index. What changes is the unit of success and the page shapes that earn it.

Where AI answers actually come from

Three places. First, the model’s training data, which is months old and impossible to update on demand. Second, live retrieval: the assistant searches the web or reads specific pages at the moment it answers, which is how ChatGPT, Perplexity and Copilot handle most commercial questions. Third, a search index such as Google’s, which powers AI Overviews and much of Gemini.

Two practical consequences follow. Your robots.txt now matters twice: block GPTBot, PerplexityBot, ClaudeBot or Google-Extended and you have removed yourself from the pool before the race starts. And freshness counts for more than it used to, because a retrieval system can quote a page it crawled this week. A short, factual summary at /llms.txt gives those systems an unambiguous starting point, which is why we publish one.

The four levers that decide who gets cited

Strip away the noise and GEO comes down to four controllable things, in this order:

• Crawl access: the assistant's bots can actually fetch your pages, and key content is not hidden behind client-side rendering.
• Entity clarity: one canonical name, one Organisation schema node with real sameAs links, named authors, published prices, and the same details everywhere on the web.
• Answer structure: question-shaped headings followed immediately by a self-contained 40 to 60 word answer a model can lift verbatim.
• Structured data: Organization, WebSite, Service with real Offers, FAQPage and Article with a named Person author, all matching the visible copy exactly.

Off-site corroboration decides ties: when two sources say the same thing, the model trusts the one other sites agree with. That is digital PR, directory consistency and case studies with named brands and numbers doing their quiet work.

For the full doing, read our tactical guide on how to get cited by ChatGPT, Gemini and Perplexity, which walks each lever with checklists. The commercial side of the same work is on our AI SEO page.

Who actually needs GEO

Any brand whose buyers research before they buy. If your customers ask assistants what things cost, who is best, or how something works, you are already being represented in those answers, accurately or not. High-consideration purchases feel it first: software, professional services, travel, premium ecommerce. Low-consideration, impulse categories feel it last.

The brands that should move now are the ones seeing the early symptom in Search Console: impressions holding while clicks soften. That pattern usually means the click became an answer. We unpacked it in the AI Overviews guide.

How to measure it without guessing

Keep a fixed set of 20 to 30 prompts your buyers would genuinely type, run them monthly across ChatGPT, Gemini and Perplexity, and log three things per prompt: were you mentioned, were you linked, and who was cited instead. Pair that with referral traffic from assistant domains in your analytics and AI crawler hits in your server logs. Together those three give you a share-of-answer trend you can act on.

That measurement, plus the entity, content and schema work itself, is built into our SEO & AI Visibility subscription, from £1,250 a month plus VAT, with the prompt set and results in your monthly report. If you want the same engine across email and paid too, the Growth Bundles price it as one fixed monthly number.

Questions we get asked

Written by

Sam, co-founder, growth and paid media

Runs growth and paid media at Mesmerise Marketing. Ten years of paid and organic campaigns for challenger brands across DTC, B2B services and hospitality.

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