# AEO glossary

> Every term used in this guide, grouped by topic, with what each one shows and what it does not.

## Reading brief

- Decision: Which terms a team needs to share before it reports on AI search.
- Evidence: Plain definitions, each with what the term shows and what it does not.
- Action: Agree the measurement terms first, then the rest as the programme needs them.

Terms are grouped by topic. Where a chapter of this guide explains a term in depth, the entry links to it.

## Foundations

- **AEO**: Answer engine optimization: the practice of making content easy for AI answer engines to find, understand, and cite.
- **AI assistant**: A conversational AI product that answers questions, drafts text, and searches the web when asked.
- **AI search**: Search experiences in which an AI model reads the question, gathers sources, and writes one answer instead of returning a list of links.
- **AI search intelligence**: The continuous measurement of how AI engines mention, rank, and cite brands, turned into ranked actions for improving that presence.
- **AI visibility**: How prominently a brand appears in the answers AI engines give, measured by mention rate, share of voice, average position, and citation share.
- **Answer engine**: A system that responds to a question with a generated answer instead of a list of links, such as ChatGPT, Gemini, or Perplexity.
- **Generative AI**: AI that produces new text, images, audio, or code from a prompt instead of only sorting or labeling existing data.
- **Generative engine**: An AI system that writes an answer from retrieved sources instead of listing ranked pages.
- **GEO**: Generative engine optimization: the practice of shaping how a brand appears in answers generated by AI engines.
- **LLMO**: Large language model optimization: another label for shaping how language models and the tools built on them represent a brand.

## AI search surfaces

- **AI Mode**: Google's dedicated AI search experience, where a question is answered with a written response and can be followed up conversationally.
- **AI Overviews**: Google's AI-written summary shown at the top of some search results, with links to supporting pages.
- **Conversational search**: Search done as a back-and-forth dialogue in full sentences instead of a string of keywords.
- **Supporting link**: A link shown beside an AI answer as a source for the claims the answer makes.

## Search basics

- **Backlink**: A link from one website to a page on another.
- **Branded query**: A search or prompt that includes a specific brand's name.
- **Featured snippet**: A highlighted excerpt at the top of Google results that answers a query directly and links to its source page.
- **Keyword**: A word or phrase a person types into a search engine.
- **People Also Ask**: A Google results feature that lists related questions, each expanding into a short answer with a source link.
- **Search intent**: The goal behind a query, usually grouped as informational, navigational, commercial, or transactional.
- **Search volume**: The estimated number of times a query is searched in a given period, as reported by a keyword tool.
- **SEO**: Search engine optimization: the practice of improving a site so it earns visibility in the organic results of search engines.
- **SERP**: Search engine results page: the page a search engine returns for a query.
- **Unbranded query**: A search or prompt that describes a need or category without naming any brand.
- **Zero-click search**: A search that ends on the results page without a visit to any website.

## How AI search works

- **AI citation**: A source that an AI answer links or lists as support for its text.
- **AI mention**: The appearance of a brand in the text of an AI answer, with or without a link.
- **Brand hallucination**: A false statement an AI engine makes about a specific brand, such as a wrong feature, price, or founder.
- **Chunking**: Splitting a page into passages so that each can be retrieved on its own.
- **Cited source**: A page or domain that an AI answer cites as evidence.
- **Context window**: The amount of text a model can consider at once, covering the prompt, retrieved sources, and its own reply.
- **Embedding**: A list of numbers that represents the meaning of a piece of text so that similar meanings sit close together.
- **Grounding**: Tying an AI answer to retrieved sources so its claims can be checked against them.
- **Hallucination**: A fluent AI statement that is false or unsupported by any source.
- **Knowledge cutoff**: The date after which a model has no training data.
- **Large language model**: A neural network trained on very large amounts of text to predict and generate language.
- **Non-determinism**: The property that the same prompt can return a different answer each time it is run.
- **Position bias**: The tendency of a model to give more weight to items at the start or end of a list or context than to those in the middle.
- **Prompt**: The question or instruction given to an AI model.
- **Query fan-out**: A technique in which an AI engine splits one question into several narrower searches, runs them, and combines the results into one answer.
- **Recency bias**: The tendency of retrieval-based answers to favor pages that are recent or recently updated.
- **Reranking**: A second pass that reorders retrieved passages by relevance before a model uses them.
- **Retrieval-augmented generation**: A method in which a model retrieves relevant documents first and then writes its answer from them.
- **Semantic search**: Search that matches the meaning of a query instead of only its exact words.
- **Token**: The unit of text a model reads and writes, usually a word or part of a word.
- **Training data**: The text a model learned from before it was released.
- **Vector search**: Retrieval that finds the passages whose embeddings sit closest to the embedding of the query.

## Measurement

- **AI referral traffic**: Website visits that arrive from a link inside an AI answer.
- **Answer volatility**: How much the answers to the same prompt change from run to run or from day to day.
- **Average position**: Where a brand sits, on average, in the ordered list of brands an AI answer gives.
- **Baseline**: The first measurement of how a brand appears in AI answers, taken before any change so later results have something to compare against.
- **Citation rate**: The share of AI answers that cite at least one page from a brand's own domains.
- **Citation share**: The share of all citations in a set of AI answers that point to a brand's own domains.
- **Competitive benchmarking**: Measuring a brand and its competitors on the same prompts and engines so that the results are comparable.
- **Engine coverage**: The set of AI engines included in a measurement.
- **Mention rate**: The share of tracked AI answers in which a brand is mentioned.
- **Prompt set**: The fixed list of buyer questions a brand tracks across AI engines, run repeatedly so results can be compared over time.
- **Prompt tracking**: Running a fixed set of prompts on a schedule and recording how a brand appears in the answers.
- **Share of voice**: A brand's mentions as a share of all brand mentions across the same set of tracked answers.
- **Tracked answer**: One recorded answer from one engine to one prompt on one run.

## Buyer behavior

- **Buyer journey**: The steps a buyer takes from first noticing a problem to making a purchase decision.
- **Category entry point**: A situation or need that leads a buyer to start thinking about a category.
- **Dark funnel**: The part of a buying journey that happens where a company's analytics cannot see it, such as private chats, peer advice, review sites, and AI assistants.
- **Dark social**: Content sharing through private channels such as messaging apps and email, where the source of a visit goes untracked.
- **Shortlist**: The small set of vendors a buyer decides to evaluate seriously.

## Content and authority

- **Answer-first content**: Content that states the answer in the opening lines of a section and then supports it.
- **Content freshness**: How recently a page was published or meaningfully updated.
- **Digital PR**: Earning coverage and links from independent publications to build a brand's presence in the sources AI engines read.
- **E-E-A-T**: Experience, expertise, authoritativeness, and trustworthiness: the framework Google's quality raters use to judge the quality of content.
- **Earned media**: Coverage of a brand by independent publishers, creators, and communities that the brand neither paid for nor owns.
- **Entity**: A distinct person, brand, product, place, or concept that a system can identify and relate to other things.
- **Entity optimization**: Making a brand and its products easy for search systems to identify, describe, and connect to the right facts.
- **Information gain**: The new information a page adds beyond what already exists on the topic.
- **Internal linking**: Links between pages on the same site that help readers and crawlers find related content.
- **JSON-LD**: A format for writing structured data as a block of JSON inside a page.
- **Knowledge graph**: A database of entities and the relationships between them.
- **Original research**: Data or findings that a publisher collected itself, giving other pages something new to cite.
- **Structured data**: Code added to a page that labels its content in a format machines can read.
- **Third-party validation**: Independent confirmation of a brand's claims from sources the brand does not control, such as reviews, press, and analyst coverage.
- **Topic cluster**: A group of pages on related questions, linked to a central page on the main topic.
- **Topical authority**: The depth and consistency with which a site covers a subject, which can make it a more credible source on that subject.

## Technical access

- **AI crawler**: An automated program that fetches web pages for an AI company, to train models, build a search index, or answer a live request.
- **Crawlability**: How easily automated crawlers can reach and fetch a site's pages.
- **Indexability**: Whether a page that has been fetched is allowed and able to be stored in a search index.
- **JavaScript rendering**: Building a page's content in the browser with JavaScript instead of sending it ready-made from the server.
- **llms.txt**: A proposed convention for a plain-text file that points language models to a site's most useful pages.
- **robots.txt**: A file at the root of a site that tells crawlers which paths they may fetch.
- **Sitemap**: A file that lists a site's pages to help crawlers find them.

## Agents and protocols

- **Agentic search**: Search in which an AI agent plans and runs several searches and reads sources across steps before giving an answer.
- **AI agent**: Software that uses an AI model to pursue a goal through several steps, calling tools along the way.
- **Model Context Protocol**: An open standard that lets AI applications connect to external tools and data through a common interface.