GEO vs SEO: what's the difference?
Short answer: GEO vs SEO comes down to where you want to be visible. SEO (search engine optimisation) is the work of ranking in Google's list of results so that people click through to your site. GEO (generative engine optimization) is the work of being cited and mentioned when ChatGPT, Gemini, Perplexity or Google's AI Overviews write an answer. The two share the same foundation, and most businesses need both, with GEO built on top of solid SEO.
What is GEO?
GEO stands for generative engine optimization (optimisation in British spelling). It means improving how often and how accurately AI systems that write answers use your content and name your business. A "generative engine" searches or recalls information, combines several sources and writes one reply, usually with a handful of links.
The term comes from research. A group of researchers led by Pranjal Aggarwal published the paper "GEO: Generative Engine Optimization" on arXiv in November 2023, and it was accepted to the KDD conference in 2024. They tested nine ways of rewriting web content against a benchmark of 10,000 queries and measured how visible each source became in the generated answer. Adding quotations, statistics and source citations worked best, with visibility gains of up to 40 percent. Keyword stuffing brought little to no improvement, and the effect of each method varied by subject area (Aggarwal et al., 2024).
Treat those figures as results from a controlled experiment. They show that verifiable, well-sourced text gets used more, and they are no promise of a 40 percent lift for your site.
You will also meet the label AEO. We explain how it overlaps with GEO in what answer engine optimization is.
What do GEO and SEO have in common?
GEO and SEO share three things: a technical foundation, useful content and authority. Google states that SEO best practices remain relevant for AI Overviews and AI Mode, and that there are no additional requirements or special optimisations for appearing in them (Google Search Central).
Technical foundation
A page that cannot be crawled cannot be ranked or quoted. For Google's AI features, a page has to be indexed and eligible to be shown with a snippet. Other assistants run their own crawlers. OpenAI says sites that block OAI-SearchBot will not be shown in ChatGPT search answers (OpenAI), and Perplexity recommends allowing PerplexityBot so that your site can appear in its results (Perplexity). Check robots.txt, your CDN and any bot protection.
Content
Both disciplines reward pages that answer a real question better than the alternatives. Google's list of best practices for AI features is ordinary SEO advice: make content findable through internal links, keep important content in text form, offer a good page experience and make sure structured data matches the visible text. If you need a refresher on the basics, start with what SEO is.
Authority
Search engines and AI assistants both lean on signals from outside your own site. In SEO that mostly means links. In GEO, plain mentions of your brand in reviews, directories, trade press and comparisons count as well, because they are the text an assistant reads when it decides who to name.
Where do GEO and SEO differ?
They differ in what counts as a result. SEO aims for a position that produces a click. GEO aims for a place inside the answer itself, as a cited source or a named recommendation.
| SEO | GEO | |
|---|---|---|
| Where you appear | The list of results in Google or Bing | Generated answers in ChatGPT, Gemini, Perplexity, Copilot, AI Overviews |
| What you win | A ranking and a click | A citation, a link or a brand mention |
| Unit that competes | The page | A passage, a fact or the brand as a whole |
| Outside signals | Mainly links | Links plus mentions and consistent facts across the web |
| Measurement | Positions, impressions, clicks | Share of answers that mention or cite you, referral visits, accuracy |
| Stability | Rankings move slowly | Answers vary between runs and users |
Citations instead of clicks
A generated answer can settle the question on the spot. Your business may be named, and influence the buyer, without a visit ever reaching your analytics. Google does say that clicks from results pages with AI Overviews are of higher quality, in the sense that those visitors are more likely to spend more time on the site (Google Search Central).
Sources and brand mentions
In SEO you compete with the pages on the results page. In GEO you also compete for what third parties say about you. If an assistant builds its answer from a "best accountants in Leeds" roundup or a review site covering roofers in Austin, your presence on those sources matters as much as your own service page. We go through the selection signals in how AI chooses which companies to recommend.
Structured direct answers
Assistants lift passages. A section that opens with a direct answer of two to four sentences, names its subject and carries its own context (country, date, price basis) is easier to quote than a long introduction. The research above points the same way: specific figures with sources beat vague claims.
What is llms.txt and does it help?
llms.txt is a proposed convention: a Markdown file, normally at /llms.txt, that gives AI agents a short, curated overview of a website and links to its most important pages. It is a proposal and has not been adopted as an official web standard. For most business sites it is optional housekeeping with no confirmed effect on visibility in AI answers.
Jeremy Howard published the proposal in September 2024. The reasoning is that HTML pages wrap their information in navigation, ads and JavaScript, and that context windows are too small to take in most websites whole. The file needs only an H1 with the name of the site or project. A short summary and lists of links with notes are optional. The proposal says the file is meant to be used on demand, when an agent needs information while helping a user, and that it complements robots.txt and sitemaps (llmstxt.org).
What it does not do:
- It does not control crawling. Access is still governed by robots.txt. OpenAI and Perplexity both document robots.txt as the way to allow or block their crawlers.
- It is not required by Google. Google says you do not need to create new machine readable files, AI text files or markup to appear in AI Overviews or AI Mode (Google Search Central).
- It is not a documented ranking or citation signal. The crawler documentation from OpenAI and Perplexity explains which bots they run and how robots.txt applies. Neither page lists llms.txt as something that affects whether a site appears in answers.
The file fits developer documentation best, where coding agents need clean reference text. If your CMS can generate one cheaply, there is little harm in having it, as long as crawl access, clear content and mentions come first.
How do you measure visibility in AI answers?
You measure it with a fixed set of prompts tested on a schedule, supported by analytics and Search Console. No assistant offers a complete report of how often it mentions you, so the picture is assembled from several partial sources.
- A fixed prompt set. Write 20 to 50 questions your customers ask, in their words: comparisons, "best for" questions, price and how-to questions. Keep the list unchanged so that results are comparable over time.
- Regular runs in several assistants. Test the same prompts every month in ChatGPT, Gemini, Perplexity, Copilot and Google. Run each prompt more than once, because answers vary. Our guide on how to appear in ChatGPT shows a simple version of this test.
- Share of answers. Record for each answer whether your brand is mentioned, whether your site is cited as a source and whether the facts are right. The share of answers that mention you is the closest GEO gets to a ranking report.
- Cited sources. Note which third-party pages the assistants link to. That list tells you where you need to be mentioned.
- Referral traffic. In your analytics, group visits from domains such as chatgpt.com, perplexity.ai, copilot.microsoft.com and gemini.google.com.
- Search Console. Google says sites appearing in AI features are included in the overall search traffic in Search Console, in the Performance report under the Web search type (Google Search Central). It is counted together with ordinary results, so you cannot view it separately there.
A made-up example of the arithmetic: 20 prompts run 3 times each give 60 answers. If your brand is mentioned in 15 of them, your mention share is 25 percent. If 6 answers also link to your site, your citation share is 10 percent. Act on the trend over several months, since one month means little.
Do you need both GEO and SEO?
Yes, in most cases, and in that order. SEO is the base layer, because Google's AI features draw on pages that are already indexed, and other assistants can only use pages their crawlers reach and understand. GEO adds the parts SEO does not cover by itself.
- Start with SEO if the site has indexing problems, thin service pages or little search visibility.
- Add GEO when the basics are in place and customers in your market ask AI assistants for recommendations. The extra work is prompt testing, getting mentioned on the sources assistants cite, keeping facts consistent everywhere and rewriting key sections as direct answers.
Ranking well does not guarantee that assistants name you, and the reverse also holds. For the GEO side as ongoing work, see our page on generative engine optimization.
