SEO vs GEO vs AEO: what's the difference, and what should you do?

What do SEO, AEO and GEO mean?

None of the three has a standard definition, and people use them loosely. Here is what each usually means, and where it comes from.

SEO: search engine optimisation

Google's starter guide says SEO "is about helping search engines understand your content, and helping users find your site and make a decision about whether they should visit your site through a search engine."² In practice that means getting pages crawled, indexed and ranked for the queries your buyers type, then earning the click. Success is a position in a list of links, measured in rankings, impressions and clicks.

AEO: answer engine optimisation

An answer engine replies with an answer instead of a list of links. Google lists AEO alongside GEO as "terms you may see used to describe work specifically focused on improving visibility in AI search experiences."¹ Some marketers use AEO more widely, to include the direct answers classic search already gave, such as Google's featured snippets, which reverse the usual result by "showing the descriptive snippet first".³ AEO grew out of marketing practice; we couldn't trace it to a single original source.

GEO: generative engine optimisation

GEO has a clear origin: a research paper titled "GEO: Generative Engine Optimization", by Pranjal Aggarwal of IIT Delhi and five co-authors, three of them at Princeton University. It was first posted on 16 November 2023 and accepted to the KDD 2024 conference.⁴

The paper called systems such as Bing Chat, Google's Search Generative Experience and Perplexity "generative engines": they retrieve sources, then write an answer grounded in them. Its central point was that rank stops describing visibility once an answer blends several sources into one block of text. So instead of rank, its main measure counted how many words of the answer drew on a source, weighted by how early they appeared.

In its tests, adding citations, quotations and statistics to a page raised that measure by 30 to 40%. Keyword stuffing, a classic SEO tactic, gave "little to no improvement", and on Perplexity itself it did 10% worse than leaving the page alone.⁴ Read those numbers as a direction, not a forecast: most tests ran on the authors' own benchmark and answer engine, built on the top five Google results for each query.

The term has since reached the platforms. Microsoft called its AI Performance report in Bing Webmaster Tools "an early step toward Generative Engine Optimization (GEO) tooling".⁵ For what GEO asks of your own website, and how to check it by hand, see What is GEO?

Is AEO different from GEO?

Barely. Both describe the work of appearing in AI answers, and the tactics and measures are the same. They differ in origin and, for some people, in scope:

Google doesn't separate either from SEO: "From Google Search's perspective, optimizing for generative AI search is optimizing for the search experience, and thus still SEO."¹ Use whichever word your team and your buyers recognise. If someone sells AEO and GEO as two services, ask what they would do differently for each.

How do SEO and GEO compare at a glance?

Where is the work the same?

Most of what makes a site rank also makes it usable as a source for AI answers. Four areas carry over almost unchanged.

Crawling and indexing

For Google's AI features there are no extra technical hurdles: "To be eligible to be shown as a supporting link in AI Overviews or AI Mode, a page must be indexed and eligible to be shown in Google Search with a snippet", and there are "no additional technical requirements".⁶

The other engines read the web with their own search crawlers: OpenAI's OAI-SearchBot, Anthropic's Claude-SearchBot and PerplexityBot. OpenAI says sites that opt out of OAI-SearchBot "will not be shown in ChatGPT search answers".^{7, 8, 9} So the SEO habit of checking robots.txt and firewall rules now covers more bots.

There is one new switch. Search Console has a Search generative AI control that can exclude a site's links and content from AI Overviews and AI Mode. Including them is the default, so check that nobody has changed it.¹⁰

Content that answers the question

Google says that content people find unique, compelling and useful "will likely influence your website's presence in generative AI search in the long run more than any of the other suggestions in this guide."¹ It contrasts commodity content built on common knowledge with first-hand, expert content. A page that answers a buyer's question with specific facts and your own experience serves both channels.

A clear entity

Search engines and AI engines both need to connect your name with what you do, who it's for and your website. Say it plainly on your home and about pages, keep the facts consistent on your profiles elsewhere, and add Organization structured data. Structured data isn't required for Google's AI features, but Google says it's still a good idea for rich results.¹ The GEO audit checks these signals along with access and readability.

Authority and mentions elsewhere

Links and mentions from other sites have long been part of SEO. AI answers use them more directly: Google says its AI features "can show what's being said about products and services across the web, including in blogs, videos, and forum discussions." It also warns that "seeking inauthentic 'mentions' across the web isn't as helpful as it might seem."¹ Earned reviews, comparisons, interviews and forum answers help in both.

Where do SEO and GEO differ?

The goal: a link in a list, or a place in the answer

In classic search the engine shows a list and the user chooses. In an AI answer the engine has done the choosing: it names a few brands and links a few pages. The GEO paper puts it plainly: average ranking is a good measure of visibility in traditional search engines, but "this does not apply to generative engines."⁴

Being mentioned and being cited are separate wins. An answer can recommend your product while citing a review site, or cite your blog post while recommending a competitor. Track both.

The engines: one index, or several

SEO mostly means Google, and Bing. GEO spans several engines that each decide differently.

Google's AI features draw on Google's own index. They retrieve pages through its core ranking systems and use "query fan-out": "a set of concurrent, related queries generated by the model". For "how to fix a lawn that's full of weeds", Google's example fan-out queries include "best herbicides for lawns".¹ A page can be cited because it ranks for one of those side questions, not the one the user typed. Even Google's two features differ: "AI Mode and AI Overviews may use different models and techniques, so the set of responses and links they show will vary."⁶

ChatGPT, Claude and Perplexity read the web with their own crawlers, so a strong Google ranking is no guarantee of a mention there.

The measures: rankings and clicks, or share of answers

SEO measures are mature: rankings, impressions, clicks and click-through rate, in Search Console and your analytics. Traffic from AI Overviews and AI Mode is counted in the same Performance report, in the Web search type.⁶

First-party GEO reporting is newer and narrower. By 31 August 2026 Google had rolled out a Generative AI performance report in Search Console to all sites. It shows how often links to your pages appeared in AI Overviews and AI Mode.¹¹ Bing's AI Performance report, launched as a public preview in February 2026, shows how often Microsoft Copilot, Bing's AI summaries and some partner services cited your pages, and the grounding queries behind those citations.⁵

Both count links to your pages. Neither tells you whether an answer named your brand without linking to you, which competitors it named instead, or what ChatGPT, Perplexity, Claude or Grok said. For that you collect the answers to a fixed set of buyer questions and count:

• Visibility: the share of answers that mention you.
• Share of voice: your mentions against your competitors'.
• Citation rate: how often your own pages are cited.
• Cited sources and who is named instead: the pages and brands the engines prefer.

How to track your brand in AI search covers each of these in detail.

Volatility: a rank, or a sample

Rank tracking reads one position per query. An AI answer is closer to a sample. Google says AI Overviews appear only when its systems judge them additive to classic search, "and as such, often don't trigger."⁶ In the answers sirefs collects, the same question on the same engine often names a different set of brands from one day to the next, while the share of answers that name a given brand moves far less.

So read GEO numbers as rates over many answers, with a sample size and an interval, and don't react to a single answer. Reading the numbers shows how.

What should you measure for each?

What should you do next?

If you're deciding where to spend effort, this is the order we'd follow:

1. Keep your SEO foundations. They're the base for AI answers too, so don't start a parallel programme.
2. Remove what blocks engines. Check that each engine's search crawler can reach your pages, that key pages are indexable and allow snippets, and that Search Console's generative AI control is set to include. The free check scores your site on the 26 checks in the GEO audit.
3. Find out where you stand in AI answers. Write down the questions buyers ask before they know your name, ask them on the engines they use, and note who is named and which pages are cited.
4. Close the gaps with pages and placements. For each question where competitors appear and you don't, read the pages the engines cite. Write the page that answers that question better, with specific facts, and work on appearing in the third-party sources they keep citing.
5. Report both channels. Use Search Console for search and answer share for AI, and judge changes on many answers, not one.
6. Vet vendors. Ask any GEO or AEO tool or agency which engines it covers, whether it collects the consumer apps or a developer API, and whether it shows sample sizes. Google warns against tools that "claim to use 'internal' Google metrics", because "No third-party tool has access to our internal ranking or AI systems."¹ Our guide to AI visibility tools compares the options.

Which GEO and AEO claims are myths?

Google says many suggested GEO and AEO "hacks" "aren't effective or supported by how Google Search actually works", and it has answered the most common claims.¹ Its answers cover Google Search, AI Overviews and AI Mode included, not other engines.

• "You need an llms.txt file." Not for Google. Google says you don't need "machine readable files, AI text files, markup, or Markdown" because Google Search doesn't use them, and that keeping an llms.txt file "will neither harm nor help your site's visibility or rankings in Google Search".¹ Keeping one for other services that read it is fine.
• "AI search needs special schema markup." Google: "there's no special schema.org markup you need to add." Structured data still helps with rich results.¹
• "Break your content into small chunks." Google: "There's no requirement to break your content into tiny pieces for AI to better understand it", and there's "no ideal page length".¹
• "Rewrite everything for AI." Google: "You don't need to write in a specific way just for generative AI search."¹ Clear writing for people is what counts.
• "AI Overviews have their own technical requirements." A page needs to be indexed and eligible for a snippet, with "no additional technical requirements".⁶
• "GEO replaces SEO." Weak SEO weakens GEO. Google's AI features retrieve pages from its search index through its core ranking systems, and the other engines need to crawl your pages just the same.^{1, 7}
• "More mentions, anywhere, is better." Google says seeking inauthentic mentions "isn't as helpful as it might seem".¹

Where does sirefs fit?

sirefs measures the GEO side. The free check runs the GEO audit on your site and asks three buyer questions on ChatGPT, Google AI Overviews and Perplexity. Monitoring collects answers from ChatGPT, Google AI Overviews, Google AI Mode, Gemini, Perplexity, Claude and Grok, with the collection method shown for each; Microsoft Copilot is coming. Plans start free.