Glossary
The GEO glossary.
Plain-English definitions of the terms behind AI search visibility, so you can talk about GEO with confidence.
What is GEO (Generative Engine Optimization)?
GEO, or Generative Engine Optimization, is the practice of getting a brand named and cited in the answers AI assistants like Claude, ChatGPT, Perplexity and Google AI give to buyers.
What is AI visibility?
AI visibility is how often, and how prominently, an AI assistant names your brand when people ask it questions about your category.
What is share of voice in AI search?
Share of voice in AI search is the percentage of AI answers in your category that name your brand, relative to the brands named alongside you.
What is a citation in AI answers?
A citation in an AI answer is a source the assistant links to or draws from when it makes a claim, such as a review site, a Reddit thread or a company page.
What is AEO (Answer Engine Optimization)?
AEO, or Answer Engine Optimization, is the practice of structuring content so answer engines can extract a clean, correct answer from it and cite it.
What is the difference between GEO and SEO?
GEO gets your brand named inside AI answers, while SEO gets your pages ranked in the list of search results. They share a technical foundation but aim at different outcomes.
What is answer engine optimization vs GEO?
Answer engine optimisation (AEO) and generative engine optimisation (GEO) describe substantially the same discipline: getting your brand accurately represented and cited in AI-generated answers. AEO grew out of featured-snippet and voice-search work, while GEO was coined for generative engines such as ChatGPT and Perplexity. In everyday use the two terms overlap almost completely.
What is an AI Overview?
An AI Overview is the AI-generated summary Google shows above the traditional results for some searches, produced by its Gemini models from pages retrieved for that query. It answers the question directly and links to a selection of the sources it drew on.
What is a prompt in GEO?
In GEO, a prompt is the question or request a user puts to an AI assistant, and it replaces the keyword as the basic unit of visibility tracking. Rather than asking where you rank for a term, GEO asks which brands the engine names and cites when it answers a given prompt.
What is brand grounding?
Brand grounding is how an AI assistant anchors the claims it makes about a brand in retrieved web pages rather than in its training data alone. A grounded answer about your pricing or features is drawn from live sources the engine can cite; an ungrounded one is reconstructed from whatever the model absorbed during training.
What is AI share of shelf?
AI share of shelf is the extent to which your brand is one of the few names an AI assistant gives when it answers a buying question. A search results page lists ten links; an AI answer typically recommends a handful of brands, and that short list is the shelf.
Retrieval-augmented generation (RAG)
Retrieval-augmented generation (RAG) is a technique where an AI system fetches relevant documents, often from a live web index, and passes them to a language model to ground its answer. Instead of relying only on what the model memorised during training, the answer is built from content retrieved at the moment you ask. For marketers, it means an AI assistant's description of your brand can come straight from web pages, including yours.
AI citation gap
An AI citation gap is the difference between how often AI assistants cite your content in relevant answers and how often they cite your competitors'. If ChatGPT or Perplexity answers your category's buying questions with links to rival sites and none to yours, you have a citation gap.
Entity SEO
Entity SEO is the practice of optimising for how search engines and AI systems understand the things your content is about, such as your brand and its products, rather than the keywords on the page. An entity is any distinct thing a machine can identify and connect to other things, and clear entities are the foundation of accurate AI answers.
llms.txt
llms.txt is a proposed standard: a markdown file placed at the root of a website that gives large language models a curated summary of the site and links to its most important content. It was proposed by Jeremy Howard of Answer.AI in September 2024 as a way to help AI systems use a site's key pages without wading through navigation, scripts and boilerplate HTML.
AI brand monitoring
AI brand monitoring is the practice of checking what AI assistants such as ChatGPT, Claude, Gemini and Perplexity say about your brand, and tracking how those answers change over time. It treats AI answers as a channel to be watched, the way you would monitor press coverage or search rankings.
What is Google AI Mode?
Google AI Mode is the conversational search experience inside Google Search that answers queries with a full AI-generated response and supports follow-up questions, rather than showing a ranked list of links. Since the Connected Apps rollout began in July 2026, initially in the US, AI Mode answers can also complete tasks, such as adding groceries to an Instacart cart, directly from the response.
What is an AI crawler?
An AI crawler is an automated bot run by an AI company to fetch web pages. The term covers three different jobs: collecting training data for models, building the search indexes behind AI answers, and fetching pages live when a user asks an assistant a question.
What is GPTBot?
GPTBot is OpenAI's web crawler for collecting training data for its GPT models. Blocking it in robots.txt asks OpenAI not to use your content in future training, but it does not affect your visibility in ChatGPT search, which relies on a separate crawler called OAI-SearchBot.
What is Google-Extended?
Google-Extended is a robots.txt control token that tells Google not to use your content for Gemini training or grounding. Blocking it has no effect on your presence in Google Search, AI Overviews or AI Mode.
What is zero-click search?
Zero-click search is a search that ends without a visit to any website: the user reads the answer directly on the results page or inside an AI-generated response. As AI answers handle more complex questions, a growing share of searches finish this way.
What is an answer engine?
An answer engine is a search system that responds to a query with a single synthesised answer instead of a ranked list of links. Systems such as ChatGPT, Perplexity, Google AI Mode and Claude read multiple sources and compose one response, so a brand is either included in the answer or absent from it.
What is content chunking?
Content chunking is the practice of structuring a page into self-contained sections that an AI engine can retrieve and quote on their own. Because answer engines typically pull passages rather than whole pages, each section needs to answer its question fully and name your brand without relying on the surrounding text.
What is E-E-A-T in AI search?
E-E-A-T stands for experience, expertise, authoritativeness and trustworthiness, the framework Google uses to judge content quality. AI answer engines have no direct equivalent, but they inherit its effects because they retrieve and cite sources from indexes already shaped by E-E-A-T-driven ranking.
What is AI referral traffic?
AI referral traffic is the visits a website receives when someone clicks through from an AI assistant's answer, such as a cited source in ChatGPT or Perplexity. In analytics it usually shows up under referrer hostnames like chatgpt.com and perplexity.ai.
What is prompt coverage?
Prompt coverage is the share of the buyer questions in your category that your AI visibility checks actually test. Two prompts sample a sliver of the question space; meaningful coverage spans the whole buying journey, from unbranded research questions to direct comparisons.
What is AI search?
AI search means getting answers from an AI assistant such as ChatGPT, Claude, Perplexity, or Gemini, which reads multiple sources and synthesises them into a single conversational response instead of returning a ranked page of links.
What is ChatGPT SEO?
ChatGPT SEO is the practice of getting a brand described accurately and recommended in ChatGPT's answers, both when the model replies from its trained memory and when it searches the live web through Bing's index and cited sources.
What is Perplexity SEO?
Perplexity SEO is the practice of optimizing content so Perplexity's answer engine retrieves it during its live web search and cites it as a source, which depends on crawler access, quotable page structure, and presence on domains Perplexity already trusts.
Brand hallucination
A brand hallucination is when an AI assistant presents false information about a company as fact, such as wrong pricing or a claim that the company has shut down, with nothing in the answer to signal uncertainty.
What is share of model?
Share of model is the percentage of an AI assistant's answers about a category that mention or recommend your brand, measured by running a fixed set of prompts repeatedly and counting how often each brand appears.
LLM SEO
LLM SEO is the practice of optimizing a brand's content and web presence so that AI assistants built on large language models, such as ChatGPT, Claude, Gemini, and Perplexity, describe the brand accurately and cite it in their answers. The same work is also called Generative Engine Optimization.
Agentic commerce
Agentic commerce is the buying of goods and services by an AI agent acting for a human: the person states what they need, and the agent finds suitable options and completes the purchase, often without the buyer visiting any brand website.
What is a knowledge graph?
A knowledge graph is a structured database of entities, such as companies and products, and the relationships between them; AI systems consult graphs like Google's Knowledge Graph and Wikidata to establish basic facts about a brand before answering.
Structured data for AI search
Structured data for AI search is Schema.org markup added to a page's HTML that labels entities, products, FAQs and other facts in machine-readable form, helping AI crawlers and answer engines interpret content, though most assistants still read the rendered text itself.
AI visibility audit
An AI visibility audit is a structured check of how AI assistants such as ChatGPT, Claude and Perplexity answer the prompts buyers actually ask, testing whether a brand appears in those answers and whether the description of it is accurate.
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