Glossary
The AI search glossary
79 terms behind ChatGPT, Gemini, Claude, Perplexity and Google AI, explained in plain words, with what each one means for your brand.
A
- Engines and surfacesAds in AI answersAds in AI answers are paid placements shown inside or next to AI generated answers, such as sponsored products or links in some AI search features. Where they appear, they are labelled separately from the organic answer.Also called Sponsored AI answers, AI search adsFull definition
- CommerceAgentic commerceAgentic commerce is shopping done by AI agents on a person's behalf: finding products, comparing options and, increasingly, completing the purchase.Also called Agent shopping, AI shopping agentsFull definition
- CommerceAgentic Commerce Protocol (ACP)The Agentic Commerce Protocol (ACP) is an open standard created by OpenAI and Stripe that lets AI agents, starting with ChatGPT, complete purchases with merchants on a buyer's behalf.Also called ACPFull definition
- How AI search worksAgentic searchAgentic search is when an AI assistant plans and runs its own research before it answers: it breaks a question into steps, searches several times, reads pages, compares what it finds and only then writes a reply.Also called AI research mode, Deep researchFull definition
- How AI search worksAI agentsAI agents are AI systems that take actions for a user, such as browsing sites, comparing options, filling forms or buying products, not only answering questions. As agents grow, brands need sites that agents can read and act on.Also called Autonomous agentsFull definition
- MeasurementAI brand sentimentAI brand sentiment is the tone in which AI assistants describe your brand: positive, neutral or negative, and the reasons they give.Also called Sentiment in AI answersFull definition
- MeasurementAI citationsAI citations are the links an AI assistant shows next to its answer to point to the pages it used, such as the numbered sources in Perplexity or the source links in ChatGPT and Google AI Overviews.Also called Cited sources, AI referencesFull definition
- TechnicalAI crawlersAI crawlers are bots run by AI companies that visit websites to collect content, either to train models or to fetch pages live when an assistant answers a question.Also called AI bots, LLM crawlersFull definition
- How AI search worksAI hallucinationAn AI hallucination is a confident statement from an AI model that is false or not supported by any source, such as a wrong price, a feature that does not exist or an invented quote.Also called Confabulation, Made up factsFull definition
- How AI search worksAI memoryAI memory is when an AI assistant remembers facts from past conversations, such as a user's location, job or preferences, and uses them in later answers. It means two people can get different recommendations for the same question.Also called Personalised AI answersFull definition
- MeasurementAI referral trafficAI referral traffic is the visits your website gets from people clicking links in AI assistants such as ChatGPT, Perplexity, Gemini, Claude and Copilot.Also called LLM traffic, AI trafficFull definition
- MeasurementAI share of voiceAI share of voice is your brand's share of all brand mentions in AI answers for a set of questions, compared with your competitors.Also called Share of voice in AI, Share of modelFull definition
- CommerceAI shoppingAI shopping is when people ask AI assistants what to buy and get product recommendations, often with images, prices and links, inside the answer. ChatGPT, Google AI Mode and other assistants now show products directly.Also called AI shopping answers, Conversational shoppingFull definition
- MeasurementAI visibilityAI visibility is how often, and how prominently, AI assistants such as ChatGPT, Gemini, Claude and Perplexity mention your brand when people ask questions in your category.Also called AI search visibility, LLM visibilityFull definition
- Engines and surfacesAnswer engineAn answer engine is a search tool that replies with a direct, written answer instead of a list of links. ChatGPT, Perplexity, Gemini, Claude, Copilot and Google AI Overviews all work as answer engines.Full definition
- DisciplinesAnswer engine optimization (AEO)Answer engine optimization (AEO) is the practice of getting your brand chosen as the answer by answer engines: AI assistants, AI search features and voice assistants that reply directly instead of showing a list of links.Also called AEOFull definition
- MeasurementAnswer volatilityAnswer volatility is how much AI answers to the same question change from one run to the next, or from week to week. High volatility means a single check can be misleading, so scores need many answers and a likely range.Also called AI answer varianceFull definition
- DisciplinesAnswer-first contentAnswer-first content opens with a direct answer to the question, usually in 40 to 60 words, before giving detail. AI engines often quote that opening, so answer-first pages are easier to cite.Also called Answer first writingFull definition
- MeasurementAverage positionAverage position is where your brand appears, on average, among the brands named in AI answers. Position 1 means you are usually named first. It is counted only in answers that name you.Also called AI mention positionFull definition
B
- MeasurementBrand accuracyBrand accuracy is how correctly AI answers state the facts about your brand, such as prices, features, policies, locations and leadership. Low accuracy means AI is repeating outdated or wrong information to buyers.Also called AI brand accuracy, Fact accuracyFull definition
- MeasurementBranded vs unbranded promptsBranded prompts mention your brand by name, such as is Acme good for small teams. Unbranded prompts do not, such as best project tool for small teams. Unbranded prompts show whether AI recommends you when buyers have not chosen yet.Full definition
C
- TechnicalCanonical URLA canonical URL is the preferred address of a page when the same content is available at several addresses. It is set with a link rel canonical tag, and helps search engines and AI systems treat duplicates as one page.Also called rel canonicalFull definition
- Engines and surfacesChatGPT searchChatGPT search is the part of ChatGPT that searches the web for current information and shows answers with cited sources. It decides when to search for many questions, especially about products, news and prices.Full definition
- CommerceChatGPT shopping resultsChatGPT shopping results are the product cards ChatGPT shows, with images, prices, reviews and links, when it decides a question is about buying something. OpenAI says they are chosen independently and are not ads.Also called ChatGPT ShoppingFull definition
- MeasurementCitation rateCitation rate is the share of AI answers that cite or link to your website, out of all answers to the questions you track. It shows how often AI uses your pages as a source, which is different from how often it mentions your brand.Also called AI citation rateFull definition
- DisciplinesComparison pagesComparison pages compare your product with competitors, as versus pages or alternatives pages. Buyers ask AI comparison questions all the time, and honest, well structured comparison pages are often what AI cites.Also called Versus pages, Alternatives pagesFull definition
- How AI search worksContent chunkingContent chunking is the splitting of a page into smaller passages, so an AI system can store, find and quote the most relevant part instead of the whole page.Also called Passage chunking, ChunkingFull definition
- DisciplinesContent freshnessContent freshness is how current a page is: whether its facts, prices, dates and examples are up to date. AI search engines often prefer recent sources for questions where things change.Full definition
- DisciplinesContent gapA content gap is a question or topic your buyers care about that your site does not answer well. In AI search, content gaps show up as questions where AI cites other sites, or names competitors, because you have no clear page.Full definition
- How AI search worksContext windowA context window is the amount of text an AI model can take in at once, including the question, the conversation so far and any documents or search results added to it, measured in tokens.Full definition
- Engines and surfacesConversational searchConversational search is searching by asking questions in natural language and following up, as in a chat, instead of typing short keywords.Full definition
- TechnicalCrawl budgetCrawl budget is how many pages a crawler will fetch from your site in a given time. On large sites, wasting it on duplicate or low value pages can mean important pages are crawled less often by search and AI crawlers.Full definition
E
- DisciplinesE-E-A-TE-E-A-T stands for experience, expertise, authoritativeness and trustworthiness. It comes from Google's search quality rater guidelines and describes what makes content credible.Also called Experience, expertise, authoritativeness and trustFull definition
- DisciplinesEarned mediaEarned media is coverage of your brand that you did not pay for or publish yourself, such as press articles, reviews, forum discussions, lists and social posts. AI assistants lean heavily on it when they recommend brands.Also called Third party coverage, PRFull definition
- How AI search worksEmbeddingsAn embedding is a list of numbers that captures the meaning of a piece of text, so that texts with similar meaning get similar numbers. AI systems use embeddings to find, group and compare content.Also called Vector embeddings, Text embeddingsFull definition
- DisciplinesEntity SEOEntity SEO is making sure search engines and AI models clearly understand who your brand is, what it does and how it relates to other things, such as products, people, places and topics.Full definition
G
- DisciplinesGenerative engine optimization (GEO)Generative engine optimization (GEO) is the practice of making your brand and content more likely to be mentioned, cited and recommended in answers written by AI assistants.Also called GEO, AI search optimization, LLM SEOFull definition
- Engines and surfacesGoogle AI ModeGoogle AI Mode is a conversational search experience in Google that answers complex questions with an AI written response, runs many searches behind the scenes and lets people ask follow ups.Full definition
- Engines and surfacesGoogle AI OverviewsGoogle AI Overviews are AI written summaries shown at the top of some Google search results, with links to the pages used. They grew out of Google's Search Generative Experience (SGE).Also called AI Overviews, SGEFull definition
- TechnicalGPTBotGPTBot is OpenAI's web crawler that collects publicly available pages that may be used to train OpenAI's models. It is separate from OAI-SearchBot, which powers search in ChatGPT.Full definition
- How AI search worksGroundingGrounding is when an AI model bases its answer on specific sources, such as live search results or a set of documents, instead of relying only on what it learned in training.Also called Grounded generation, Search groundingFull definition
H
- Technicalhreflanghreflang is a tag that tells search engines which version of a page is for which language or country, such as en-GB or hi-IN. It helps the right version show in each market, including in AI features built on search engines.Full definition
- How AI search worksHybrid searchHybrid search combines keyword search with vector search, so results match both the exact words in a query and its meaning. Many AI retrieval systems use it.Full definition
I
- TechnicalIndexNowIndexNow is an open protocol that lets a website tell participating search engines, such as Bing, that a page was added, changed or removed, so it can be crawled sooner. Faster indexing in Bing also helps Copilot and other features that use Bing's index.Full definition
- DisciplinesInformation gainInformation gain is how much new, useful information a page adds compared with what is already out there on the same topic. Pages with original facts, data or experience add more than pages that repeat what others say.Full definition
K
- How AI search worksKnowledge cutoffA knowledge cutoff is the date after which an AI model has no information from its training data. Anything that happened later is unknown to the model unless it searches the web or is given the facts.Also called Training cutoff, Training data cutoffFull definition
- How AI search worksKnowledge graphA knowledge graph is a database of entities, such as companies, people, products and places, and the relationships between them. Search engines and AI systems use knowledge graphs to understand who is who and what is what.Also called Entity graphFull definition
L
- How AI search worksLarge language model (LLM)A large language model (LLM) is an AI model trained on very large amounts of text to understand and write language. LLMs power assistants such as ChatGPT, Gemini, Claude, Grok and DeepSeek.Also called LLM, Foundation modelFull definition
- MeasurementLikely rangeA likely range is the span within which a score such as AI visibility probably sits, given how many answers it was measured from. A score of 30% with a range of 25 to 35% is more honest than 30% alone, because AI answers vary.Also called Confidence interval, Confidence rangeFull definition
- DisciplinesLLM optimization (LLMO)LLM optimization, or LLMO, is the work of improving how large language models describe and recommend your brand. It is another name for much of what GEO and AEO cover, with extra focus on what models learn in training as well as what they find through search.Also called LLMO, Large language model optimizationFull definition
- Technicalllms.txtllms.txt is a proposed standard: a markdown file at the root of a website that gives AI models a short summary of the site and links to its most useful pages.Full definition
M
- MeasurementMention rateMention rate is the share of AI answers that name your brand, out of all answers to the questions you track. It is the core of AI visibility, measured across engines, markets and repeated answers.Also called Brand mention rateFull definition
- Engines and surfacesMicrosoft CopilotMicrosoft Copilot is Microsoft's AI assistant, built into Windows, Edge, Bing and Microsoft 365. It grounds its answers in Bing search results, so Bing visibility matters for appearing in Copilot.Also called CopilotFull definition
- TechnicalModel Context Protocol (MCP)The Model Context Protocol (MCP) is an open standard, introduced by Anthropic, that lets AI assistants connect to outside tools and data through MCP servers, in a common way.Also called MCPFull definition
P
- CommerceProduct feedsA product feed is a structured file of a store's products, with titles, prices, stock, images and identifiers, sent to shopping platforms. Feeds help shopping results, and increasingly AI shopping answers, show your products with current facts.Also called Product data feedFull definition
- MeasurementPrompt gapA prompt gap is a buyer question where AI recommends one or more competitors but not you. Prompt gaps are the clearest list of opportunities in AI search, because they show exactly where rivals win the answer.Also called Competitor gapFull definition
- MeasurementPrompt trackingPrompt tracking is regularly asking AI assistants a fixed set of questions and recording how they answer, to measure your brand's visibility, position and sentiment over time.Also called AI rank tracking, Prompt monitoringFull definition
- MeasurementPrompt volumePrompt volume is an estimate of how often people ask AI assistants a given question or topic. Because AI platforms do not publish query data, prompt volume is usually estimated from search demand and other signals rather than measured directly.Also called AI search volumeFull definition
R
- How AI search worksRerankingReranking is a step in AI search where retrieved pages are scored again to decide which are most relevant to the question, before the model reads them. Pages that answer the exact question clearly tend to rank higher at this step.Full definition
- How AI search worksRetrieval-augmented generation (RAG)Retrieval-augmented generation (RAG) is a way of building AI answers where the system first retrieves relevant documents or web pages, then has the language model write the answer using them.Also called RAGFull definition
- Technicalrobots.txtrobots.txt is a text file at the root of a website that tells crawlers, including AI crawlers, which parts of the site they may or may not visit.Full definition
S
- How AI search worksSemantic searchSemantic search is search that understands the meaning and intent behind a query, not only its exact words, so it can return results that answer the question even when they use different wording.Full definition
- TechnicalServer-side rendering (SSR)Server-side rendering (SSR) means a web page's HTML is built on the server and sent complete to the browser or bot, instead of being assembled by JavaScript in the browser. It makes content readable to crawlers that do not run JavaScript.Also called SSR, Pre-renderingFull definition
- TechnicalSitemapA sitemap is an XML file that lists the pages on your site you want crawled, often with last modified dates. It helps search engines and other crawlers find your important pages.Also called XML sitemapFull definition
- MeasurementSources vs citationsSources are all the pages an AI engine read or retrieved while writing an answer. Citations are the subset it shows to the user as links. A page can shape an answer without being cited.Full definition
- TechnicalStructured dataStructured data is code added to a page, usually JSON-LD using the Schema.org vocabulary, that describes its content in a machine readable way, such as a product's price, an article's author or a company's logo.Also called Schema markup, Schema.org, JSON-LDFull definition
- How AI search worksSystem promptA system prompt is the hidden instruction an AI product gives its model before the user's question, setting its role, tone and rules. It shapes how answers are written, such as whether to name brands or cite sources, but users do not see it.Full definition
T
- How AI search worksTemperatureTemperature is a setting that controls how random an AI model's output is. Higher temperature gives more varied answers, lower gives more predictable ones. It is one reason the same question can get different answers.Also called Model temperatureFull definition
- How AI search worksTokenizationTokenization is how an AI model splits text into small pieces called tokens, often parts of words, before it reads or writes. Limits, costs and context windows are all measured in tokens.Also called TokensFull definition
- DisciplinesTopical authorityTopical authority is how strongly a site is seen as an expert source on a subject, built by covering that subject in depth, accurately and consistently over time.Full definition
- How AI search worksTraining dataTraining data is the text a language model learned from before release, such as web pages, books and other sources. What the web said about your brand at that time shapes how the model describes you when it answers without searching.Full definition
U
- CommerceUniversal Commerce Protocol (UCP)The Universal Commerce Protocol (UCP) is an open standard, announced by Google with Shopify and other partners in January 2026, that lets AI agents discover what a store supports and complete purchases with it in a common way.Also called UCPFull definition
- MeasurementUnlinked brand mentionsUnlinked brand mentions are places on the web where your brand is named without a link to your website. AI models learn about brands from these mentions, so they count even without a link.Also called Brand mentions without links, Implied linksFull definition
- TechnicalUser agentA user agent is the name a browser or crawler sends with each request, such as GPTBot or Googlebot. Websites and robots.txt rules use it to tell AI crawlers apart and decide what each may access.Also called User agent stringFull definition
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