Glossary

The AI search glossary, term by term.

Plain-language definitions for the new search reality. GEO, AEO, citations, share of voice, and everything in between.

69 terms · Updated October 2026

A to Z

Every term, defined

AEO audit

An AEO audit is a baseline measurement of how AI engines answer your buyer prompts: whether you are cited, your share of voice, and which sources decide each answer. Prefer runs one for free.

Agentic search

Agentic search is when an AI plans its own steps, runs several searches, reads pages and sometimes acts before it answers. Prefer tracks the sources engines cite and AI crawler visits in your logs.

AI Citation

An AI citation is the source an AI assistant such as ChatGPT or Perplexity credits in its answer for a fact or a recommendation. Prefer tracks which prompts cite your pages.

AI Crawler

An AI crawler is a bot AI companies use to fetch web pages, to train models or to source live answers, named by a user-agent such as GPTBot. Prefer's free checker shows which ones can reach you.

AI hallucination

An AI hallucination is a confident AI answer that is false or not supported by any source. Prefer shows what each engine says about your brand and the sources behind it, so you can spot one.

AI Overview

An AI Overview is the AI-written summary Google shows above some search results, with links to the pages it drew on. Prefer tracks which pages AI Overviews cite for your buyer searches.

AI Referral Traffic

AI referral traffic is website visits that arrive when a user clicks a cited link in an AI answer; ChatGPT tags them utm_source=chatgpt.com. Prefer pairs them with the citations that send them.

AI search engine

An AI search engine answers a question with a written response built from web pages it retrieves and cites, instead of a list of links. Prefer tracks how five of them answer about your brand.

Amazonbot

Amazonbot is Amazon's web crawler for improving its products and services, and it may be used to train Amazon AI models. Prefer lists its token, Amazonbot, with the robots.txt rules to use.

Answer Engine

An answer engine is a search system, such as ChatGPT, Perplexity or Google AI Overviews, that returns one sourced answer instead of a list of links. Prefer tracks five of them.

Answer Engine Optimization (AEO)

Answer Engine Optimization is the practice of structuring your content and presence so AI assistants cite and recommend your brand. Prefer tracks your citations and ships the work.

Applebot

Applebot is Apple's web crawler powering search in Siri, Spotlight and Safari, and AI answers in Siri and Search; its robots.txt token is Applebot. Prefer's free checker tests your robots.txt.

Applebot-Extended

Applebot-Extended is Apple's robots.txt control token, not a crawler; disallowing it opts content out of training Apple's foundation models. Prefer's free checker tests the rule for you.

Bingbot

Bingbot is Microsoft's standard crawler, feeding Bing search, Copilot and Bing grounding results; its robots.txt token is bingbot. Prefer's free checker tests your robots.txt for it.

Brand Authority

Brand authority is how far people, search engines and AI models trust your brand as a credible source on a topic. Prefer shows how often AI engines name you against your competitors, and why.

Brand mention monitoring

Brand mention monitoring is tracking where your brand is named across AI answers and the web, and whether each mention also cites your site. Prefer monitors both in AI answers.

Brand Sentiment

Brand sentiment is the overall tone, positive, neutral or negative, in how people and AI answers talk about your brand. Prefer measures the sentiment of each AI mention alongside share of voice.

CCBot

CCBot is Common Crawl's crawler for an open web dataset that is widely used to train AI models; you control it in robots.txt with the token CCBot. Prefer's free checker tests your rules for it.

ChatGPT search

ChatGPT search lets ChatGPT search the live web, read pages and cite them in its answer, instead of answering from memory. Prefer tracks which pages it cites for your buyer prompts.

ChatGPT-User

ChatGPT-User is the OpenAI user agent that visits a web page when a ChatGPT or Custom GPT user's question needs it; it does not crawl automatically. Prefer's Agent Analytics shows its visits.

Citation Rate

Citation rate is the percentage of tracked prompts where an AI engine cites your website as a source, not just names your brand. Prefer measures it across five AI engines.

Claude-SearchBot

Claude-SearchBot is Anthropic's crawler that indexes web content to improve Claude's search results; you control it in robots.txt by its token. Prefer's free checker tests your rules for it.

Claude-User

Claude-User is the agent Anthropic's Claude may use to access websites when people ask it questions; you control it in robots.txt by its token. Prefer's free checker tests your rules for it.

ClaudeBot

ClaudeBot is Anthropic's crawler that collects public web content that could contribute to training its AI models; you allow or block it in robots.txt as ClaudeBot. Prefer's free checker tests for it.

Context window

A context window is all the text a language model can take into account while writing a response, measured in tokens. Prefer shows which sources make it into AI answers about your category.

Conversational Search

Conversational search is searching by asking questions in plain language and following up in a dialogue, as in ChatGPT or Google AI Mode. Prefer tracks how those engines answer your buyers.

Crawl Budget

Crawl budget is the set of URLs a search engine can and wants to crawl on your site, set by your server's capacity and its demand. Prefer's Agent Analytics shows which AI crawlers visit.

Digital PR

Digital PR is earning coverage, mentions and links on trusted third-party sites such as publications, reviews and listicles. Prefer shows which of those sources AI engines cite for your category.

DuckAssistBot

DuckAssistBot is DuckDuckGo's crawler that fetches pages in real time for its cited AI-assisted answers, and is not used to train AI models. Prefer's robots.txt guides show how to keep it allowed.

E-E-A-T

E-E-A-T stands for experience, expertise, authoritativeness and trustworthiness, Google's framework for judging content quality. Prefer shows which trusted sources AI engines cite in your category.

Entity SEO

Entity SEO is the work of making search engines and AI systems recognize your brand as a distinct thing with consistent facts. Prefer shows whether AI engines name and describe you correctly.

FAQ schema

FAQ schema is FAQPage structured data that marks up question and answer pairs so machines can read them. Prefer's free FAQ schema generator builds valid JSON-LD for it.

Featured snippet

A featured snippet is a passage Google lifts from one page and shows in a box above the regular results. Prefer tracks the AI answers that now sit above it, and which pages they cite.

Generative Engine Optimization (GEO)

Generative engine optimization (GEO) is the work of getting your brand named and cited in AI answers from tools like ChatGPT, Gemini and Perplexity. Prefer tracks your citations and ships the work.

Google AI Mode

Google AI Mode is Google's conversational search: one AI-written answer built from hidden sub-queries, citing the sources it retrieves. Prefer tracks whether AI Mode cites you.

Google-Extended

Google-Extended is a robots.txt control token, not a crawler, that governs whether Google uses your content for Gemini training and grounding. Prefer's free checker tests your robots.txt for it.

Googlebot

Googlebot is Google Search's web crawler, and its robots.txt rules also govern AI Overviews and AI Mode. Prefer's free checker tests your robots.txt for it, and Prefer tracks both AI features.

GPTBot

GPTBot is OpenAI's crawler that collects public web pages to help train its models; you allow or block it in robots.txt by its user-agent, GPTBot. Prefer's free checker tests your robots.txt for it.

Grounding

Grounding is when an AI system builds its answer from sources it retrieves at query time, not from its trained-in memory, so it can cite pages. Prefer shows which pages engines cite on your prompts.

Knowledge graph entity

A knowledge graph entity is a real-world thing, such as a company, product or person, that an AI system recognizes and attaches verified facts to. Prefer checks whether AI engines know yours.

Knowledge panel

A knowledge panel is the information box Google shows for a person, place, organization or thing in its Knowledge Graph. Prefer shows how AI engines describe that same brand in their answers.

Large language model (LLM)

A large language model (LLM) is an AI model trained on huge amounts of text to predict the next word, which lets it write answers. Prefer tracks what LLM-powered engines say about your brand.

LLM Optimization (LLMO)

LLM optimization (LLMO) is the work of getting AI assistants such as ChatGPT and Gemini to mention, recommend and cite your brand. Prefer measures whether it is working, on five engines.

LLM Visibility

LLM visibility is how often a brand appears, is cited and is recommended in the answers large language models like ChatGPT and Gemini generate. Prefer measures it on five AI engines.

llms.txt

llms.txt is a proposed standard: a markdown file at a site's root that gives AI models a curated map of its most important pages. Prefer's free generator builds one in the browser.

Meta-ExternalAgent

Meta-ExternalAgent is Meta's web crawler for training AI models and indexing content, controlled in robots.txt by the token meta-externalagent. Prefer's free generator writes your other AI bot rules.

Meta-ExternalFetcher

Meta-ExternalFetcher is Meta's fetcher for links a user asks for, including agentic AI tasks; Meta says it may bypass robots.txt. Prefer lists its token, meta-externalfetcher, with the rules to use.

MistralAI-User

MistralAI-User is Mistral AI's fetcher that visits a page when a user asks its assistant, Vibe, a question, and may link the page as a source. Prefer's guides show how to allow it in robots.txt.

Multimodal Search

Multimodal search is searching with more than text: a photo, a voice question, or a video, often mixed with words. Prefer tracks the text prompts and cited sources behind AI answers on five engines.

OAI-SearchBot

OAI-SearchBot is OpenAI's crawler that surfaces websites in ChatGPT's search features; block it and your pages are not shown in ChatGPT search answers. Prefer's free checker tests for it.

Parasite SEO

Parasite SEO is publishing on a high-authority site you do not own, like Reddit or LinkedIn, to borrow its reach. Prefer does the authentic version on Enterprise and Prefer Managed.

People Also Ask

People Also Ask is the box of related questions Google shows in results, each expanding to a short answer from a web page. Prefer tracks the buyer questions AI engines answer about your category.

Perplexity-User

Perplexity-User is the agent Perplexity uses to visit a page when a user asks a question. Prefer's free checker tests your robots.txt for it, though Perplexity says it generally ignores those rules.

PerplexityBot

PerplexityBot is Perplexity's crawler for surfacing and linking websites in its search results, not for training models; you control it in robots.txt. Prefer's free checker tests your rules for it.

Prompt tracking

Prompt tracking is running a fixed set of buyer prompts across AI engines on a schedule to record when your brand is mentioned or cited. Prefer runs yours on five engines.

Query fan-out

Query fan-out is how AI search splits one prompt into many hidden sub-queries, retrieves sources for each, and merges them into one cited answer. Prefer logged a mean of 4.8 per ChatGPT question.

Retrieval-augmented generation (RAG)

Retrieval-augmented generation (RAG) is when a language model fetches relevant documents first, then writes its answer from them. Prefer tracks which retrieved pages AI engines cite about you.

Schema markup

Schema markup is code, usually JSON-LD, that labels the things on a page (an organization, a product, a question) with the schema.org vocabulary. Prefer's free schema generator builds clean markup.

Search everywhere optimization

Search everywhere optimization is the practice of being findable on every platform people search, from Google to AI engines, YouTube and Reddit. Prefer covers the AI engine part of that map.

Search Generative Experience (SGE)

Search Generative Experience (SGE) was Google's 2023 Search Labs experiment that put AI-generated answers at the top of search, and the forerunner of AI Overviews. Prefer tracks AI Overviews today.

Semantic Search

Semantic search finds results by matching the meaning of a query, not only its exact words. Prefer shows which pages AI engines retrieve and cite for your buyer prompts, so you see what it surfaces.

Share of Voice (AI Search)

Share of voice in AI search is the percentage of tracked prompts where an AI model names your brand, against the competitors in the same answers. Prefer measures it on five engines.

Structured data

Structured data is a standard format, usually schema.org vocabulary in JSON-LD, that labels what a page is about so machines can read it. Prefer's free schema generator builds it in minutes.

Topical authority

Topical authority is the trust a site earns by covering one subject in depth, so engines treat it as a go-to source. Prefer writes that depth of content on every self-serve plan.

Training Data

Training data is the large body of text a language model learns from before release, which becomes its built-in memory. Prefer tracks the live, cited answers you can actually influence.

Unlinked Brand Mentions

An unlinked brand mention is a page that names your brand in its text without linking to your site. Prefer tracks whether AI answers name you, which unlinked mentions can feed.

User-Agent

A user-agent is the string a browser or bot sends with each web request to say what it is, such as GPTBot. Prefer's free AI Crawler Access Checker tests which AI user-agents your robots.txt allows.

Vector embeddings

Vector embeddings are lists of numbers that represent the meaning of text, so similar ideas sit close together. Prefer tracks which pages AI engines retrieve and cite once that matching is done.

Zero-Click Search

Zero-click search is a search that ends without a click to any website, because the answer appears on the results page or in an AI assistant's reply. Prefer tracks whether that answer names you.

Go deeper

GEO hub Generative engine optimization, explained What a GEO tool should do, and how brands win citations in AI answers. AEO hub Answer engine optimization, explained What AEO is, how it differs from SEO, and the tools that track it. Roundup The best GEO tools in 2026, tested and compared The category shortlist, with real prices and honest verdicts.

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