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AEO (answer engine optimization), GEO (generative engine optimization) and AI Search Optimization are three names for the same goal: being cited in the answers that AI assistants such as ChatGPT, Perplexity and Gemini give. This glossary by Oltre Digital defines the terms a professional firm meets when it works on its AI visibility, in plain English and with sources.
What is the difference between SEO, AEO, GEO and AI Search Optimization?
| Term | Stands for | Goal | Where it shows |
|---|---|---|---|
| SEO | Search engine optimization | Rank in the list of results | Google, Bing |
| AEO | Answer engine optimization | Be used as the answer | Featured snippets, voice assistants, AI assistants |
| GEO | Generative engine optimization | Be cited in answers written by AI | ChatGPT, Perplexity, Gemini, Copilot, AI Overviews |
| AI Search Optimization | Oltre Digital’s umbrella term | Be understood, trusted and cited by AI assistants | All of the above, built on good SEO |
What is AEO (answer engine optimization)?
AEO, short for answer engine optimization, is the practice of structuring content so that an answer engine uses it as the answer. An answer engine is a search feature or assistant that replies with an answer instead of a list of links: featured snippets and voice assistants first, AI assistants such as ChatGPT, Perplexity and Gemini today.
What is GEO (generative engine optimization)?
GEO, short for generative engine optimization, is the practice of making content visible in the answers that generative AI writes. The term comes from a research paper by Pranjal Aggarwal and co-authors, “GEO: Generative Engine Optimization”, first published on arXiv in November 2023.
The paper measured how changes to a page, such as adding statistics, quotations and sources, affect how visible it is in generated answers.
What is AI Search Optimization?
AI Search Optimization is the umbrella term Oltre Digital uses for AEO and GEO together: making a business understandable, trustworthy and citable by AI assistants. It combines pages that answer real questions, consistent information about the business across the web and a site that AI crawlers can read. See the AI Search Optimization service.
What is an AI Overview?
An AI Overview is the summary that Google writes with its Gemini models at the top of some search results, with links to the sources it used. Google started rolling AI Overviews out to everyone in the United States in May 2024, with more countries following (Google, May 2024). For a firm, being one of the linked sources matters more than ranking just below the summary.
What is a large language model (LLM)?
A large language model, or LLM, is the AI model behind assistants such as ChatGPT, Claude and Gemini. It is trained on large amounts of text and generates answers word by word. What it “knows” without searching comes from its training data, which has a cut-off date.
What is a search-grounded answer?
A search-grounded answer is an answer that an AI assistant writes after searching the web, instead of relying only on its training data. Perplexity, ChatGPT with search, Copilot and Google’s AI Overviews work this way, which is why they can cite recent pages and why a well-indexed site has a better chance of being used. The technical name is retrieval-augmented generation (RAG).
What is a citation in an AI answer?
A citation is a source that an AI assistant names or links in its answer. Citations are the main measure of AI visibility: Oltre Digital counts, every month, whether a firm is cited for the questions its clients ask, in which position and next to which competitors.
What is an entity, and why does consistency matter?
An entity is a thing that search engines and AI models recognise as unique: a firm, a person, a place. They build their picture of an entity from every source that mentions it. When the name, description, address and services of a firm are the same on its website, Google Business Profile, LinkedIn and directories, the entity is easier to recognise, and easier to recommend.
What is structured data (schema.org)?
Structured data is a description of a page written for machines, usually in JSON-LD using the schema.org vocabulary. It tells search engines and AI assistants, without ambiguity, that a page is about an organisation, a person, a service or a list of questions and answers. On this website every page carries it: the firm as ProfessionalService, the founder as Person, services as Service and FAQs as FAQPage.
What is a zero-click search?
A zero-click search is a search that ends without the user clicking any result, because the answer is already on the results page. According to Bain & Company, about 60% of searches now end this way (Bain & Company, February 2025). The click that remains goes to the source that looks most specific.
What are AI crawlers?
AI crawlers are the bots that AI companies use to read websites, either to train models or to answer questions in real time. The main ones are GPTBot, OAI-SearchBot and ChatGPT-User (OpenAI), PerplexityBot, ClaudeBot (Anthropic) and Bingbot, whose index also feeds ChatGPT search and Copilot. Google-Extended is not a crawler but a robots.txt token: it controls whether content Google crawls may be used for Gemini. A site that blocks these bots, often by accident through a CDN setting, cannot be cited.
What is llms.txt?
llms.txt is a plain-text file at the root of a website that summarises the site and links to its most useful pages for AI tools. It was proposed by Jeremy Howard on 3 September 2024 (llmstxt.org). It is cheap to publish, but its effect on how often a site is cited has not been demonstrated; Oltre Digital publishes one and does not rely on it.
What is IndexNow?
IndexNow is a protocol that lets a website tell search engines immediately when a page is added, updated or deleted, instead of waiting to be crawled. Bing, Yandex, Seznam, Naver and other engines share the submissions (IndexNow FAQ). Because ChatGPT search and Copilot draw on Bing, faster indexing in Bing also helps AI visibility.
What is E-E-A-T?
E-E-A-T stands for experience, expertise, authoritativeness and trustworthiness, the aspects of content quality that Google says its systems try to identify, with trust as the most important (Google Search Central). For a professional firm it means named authors with real credentials, sources for every figure and a clear owner of the site.
Frequently asked questions
Is AEO the same as GEO?
In practice, yes. Both mean making content usable by systems that answer instead of listing links. AEO is the older term, born with featured snippets and voice search; GEO was coined in 2023 for answers written by generative AI.
Does AEO replace SEO?
No. AI assistants that search the web rely on search indexes, so a site that is fast, indexed and clear is the base of both. AEO and GEO add answer-first pages, entity consistency and the monitoring of citations.
Which AI assistants matter most for a professional firm?
The ones its clients use: in Europe mainly ChatGPT, Google’s AI Overviews and Gemini, Copilot and Perplexity. Oltre Digital checks all of them with the same panel of questions.
How can I see whether AI assistants cite my firm?
Ask them the questions your clients ask, in their languages, and note who is cited. Oltre Digital does this for free with the AI Visibility Scan.
Free tool
How do AI assistants describe your firm today?
With the free AI Visibility Scan, Oltre Digital checks what ChatGPT, Perplexity and Gemini say about your business and sends you the results.