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AI search glossary: GEO, AEO, LLM visibility and more

Short, plain-English definitions of the terms you will meet in generative engine optimization and AI search visibility. Each definition states what the term means first, then why it matters.

Generative Engine Optimization (GEO)

The practice of making a brand more likely to be found, understood and cited by AI systems that generate answers, such as ChatGPT, Gemini, Perplexity and Google AI Overviews, rather than only appearing in a list of search results.

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Answer Engine Optimization (AEO)

The practice of structuring content so it directly and clearly answers specific questions, for featured snippets, voice assistants and AI-generated answers.

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LLM visibility

How often, and how accurately, an AI chatbot mentions, cites or recommends a brand when answering relevant questions. It is an outcome measured per platform and per set of prompts.

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AI citation

A link or attribution shown alongside an AI-generated answer, pointing to the page the system used to support a claim. Citation behaviour differs between AI systems.

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Retrieval-augmented generation (RAG)

A technique in which an AI system first retrieves relevant text from a search index or knowledge base, then uses it as context to write its answer, instead of relying only on what the model learned in training.

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AI hallucination

An AI-generated statement that is false or unsupported but delivered with confidence, such as an outdated price or a service a company never offered.

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AI Overviews

Google's AI-generated summaries shown at the top of some search results, which synthesise several sources and link to them. Google's documentation says standard Search technical requirements apply to appearing in them.

Entity

A distinct, well-defined thing a machine can reason about, such as a company, with a clear name, category, location, products and relationships. Entity SEO is the work of making a brand a clear, consistent entity.

Knowledge graph

A large map of entities and the relationships between them that search and AI systems use to understand who and what is being discussed.

Structured data (schema markup)

Code, usually JSON-LD using the schema.org vocabulary, that states facts about a page or business in a machine-readable form, such as an organisation's name, address or FAQ.

llms.txt

A proposed, informal convention: a Markdown file at a site's root that lists key pages with short descriptions for AI systems. It is not a formal standard, and no major AI vendor has published documentation committing to use it.

Prompt panel

A fixed set of realistic buyer questions run across AI engines on a schedule, then scored for whether a brand is named, recommended and described accurately. It is the AI-era equivalent of rank tracking.

Brand mention

Any time an AI answer names a brand, whether or not it links to it, cites it or recommends it. It is the broadest and lowest-bar AI visibility outcome.

AI recommendation

An AI answer that names a brand as a suggestion, not just as a cited fact. It requires an evaluative judgment and is often influenced by third-party reviews and comparisons.

Source selection

The step in which an AI system narrows everything it retrieved down to the few sources it uses or cites in the visible answer. Vendors do not publish how it works.

Query fan-out

A technique in which an AI search system splits a question into several related sub-searches, gathers sources for each, and combines them into one answer. Google's documentation describes it for AI Overviews and AI Mode.

Semantic search

Search based on the meaning and intent of a query instead of only literal keyword matching, usually using vector embeddings, so related wording can still match.

E-E-A-T

Experience, Expertise, Authoritativeness and Trust: the quality criteria Google's rater guidelines describe. In practice they translate into concrete signals such as visible author credentials, accurate business identity and independent citations.

AI crawler

A bot operated by an AI company. Different bots do different jobs: training, search indexing or live retrieval triggered by a user, so blocking one does not block the others.

Zero-click search

A search where the user gets the answer on the results page or in an AI answer and does not click through to any website.