GEO and AEO glossary: AI search terms explained
Short, accurate definitions of the terms behind Generative Engine Optimization, Answer Engine Optimization and AI search, from AI Overviews and RAG to llms.txt and Google-Extended. Each definition links to a tool or guide where you can go deeper.
A
AEO (Answer Engine Optimization)
The practice of structuring content so answer engines and search features can extract it as a direct answer. AEO focuses on clear questions, concise answers, headings, lists and FAQ content. It overlaps heavily with GEO.
Related: Complete GEO guide
AI crawler
An automated bot that fetches web pages for an AI product, either to build a search index, to answer a user request in real time or to collect training data. Examples include OAI-SearchBot, PerplexityBot, ClaudeBot and GPTBot.
Related: AI crawler checker
AI Mode
A conversational search experience in Google Search that answers complex questions with an AI generated response and links. Like AI Overviews, it is part of Google Search and relies on Googlebot crawling.
AI Overviews
AI generated summaries shown at the top of some Google Search results, with links to supporting pages. Eligibility depends on being indexed in Google Search. Blocking Google-Extended does not remove a site from AI Overviews.
AI visibility
How often and how prominently a brand or page appears, is mentioned or is cited in AI generated answers. It varies by prompt, user, location and time, so it can only be measured from observed answers, not inferred from site quality.
Related: Run a live AI visibility test
Answerability
How easily a page can be used to answer a specific question: a direct answer near the top, clear headings, defined terms, lists and enough context to be understood when quoted on its own.
C
Canonical URL
The preferred URL for a page when several URLs show the same or very similar content, declared with a rel="canonical" link. Consistent canonicals, internal links and sitemaps help search engines consolidate signals on one URL.
ChatGPT search
The web search feature inside ChatGPT, which retrieves current pages and shows linked sources. Pages are indexed for it by OAI-SearchBot, which is separate from the GPTBot training crawler.
Citation
A link or explicit reference to a source inside an AI generated answer. Being cited usually requires that the page is crawlable, relevant to the question and contains a clear, quotable statement.
Citation potential
A measure of how likely a site is to be used as a source, based on independent references, source diversity and the presence of authoritative third party mentions. It is one of the six GEO score dimensions.
Related: GEO score dimensions
Common Crawl
A non profit that publishes a large open archive of web pages collected by its CCBot crawler. The dataset is widely used to train language models.
E
E-E-A-T
Experience, Expertise, Authoritativeness and Trustworthiness: concepts from Google's Search Quality Rater Guidelines used to describe content Google aims to reward. Trust is treated as the most important of the four.
Entity
A uniquely identifiable thing, such as an organisation, person, product, place or concept, that search engines and language models can recognise and connect to facts. Clear, consistent entity information helps machines understand who you are.
Related: Entity SEO guide
Entity clarity
How explicitly a website states who it is, what it offers, for whom and where, and how well that matches independent sources. One of the six GEO score dimensions.
F
FAQ schema
FAQPage structured data that marks up question and answer pairs visible on a page. It makes the structure explicit to machines. Google currently shows FAQ rich results only for a limited set of authoritative sites.
Related: Schema generator
G
GEO (Generative Engine Optimization)
The practice of improving how a website is crawled, understood and cited by AI powered search and answer systems such as ChatGPT, Gemini, Perplexity, Claude and Google AI Overviews. The term was popularised by a 2023 research paper from Princeton University and collaborators.
Related: Complete GEO guide
GEO audit
A structured review of the signals that affect AI search readiness: crawl access, technical setup, content answerability, entity clarity, independent sources and any available AI visibility evidence.
Related: Run a free GEO audit
GEO score
A 0 to 100 measure of how ready a page is to be crawled, understood and cited by AI search engines. GEO Score Checker calculates it from 22 checkpoints in four categories: Content Quality (30%), AI Readiness (25%), Technical Basis (20%) and Authority & Trust (25%).
Related: GEO score methodology
Google-Extended
A robots.txt user agent token, not a separate crawler, that controls whether content Googlebot fetches may be used to train and ground Gemini models. It does not affect Google Search rankings or AI Overviews.
Related: Check Google-Extended
GPTBot
OpenAI's crawler for collecting content that may be used to train its models. Blocking GPTBot opts a site out of training but does not remove it from ChatGPT search, which uses OAI-SearchBot.
Related: Check GPTBot access
Grounding
Connecting an AI model's answer to retrieved sources, such as search results or documents, so the response reflects current, verifiable information instead of only the model's training data.
H
Hallucination
A confident but false statement produced by a language model. Clear, consistent facts on your own site and in independent sources reduce the chance that AI answers misstate details about your brand.
J
JSON-LD
JavaScript Object Notation for Linked Data, the structured data format Google recommends. It sits in a script tag and describes entities on the page using Schema.org vocabulary.
Related: Schema markup guide
K
Knowledge Graph
Google's database of entities and the relationships between them. Being recognised as an entity, with consistent facts across trusted sources, can lead to a knowledge panel and clearer understanding in AI answers.
L
Large language model (LLM)
An AI model trained on large amounts of text to understand and generate language. ChatGPT, Gemini, Claude and Llama are built on LLMs.
llms.txt
A proposed Markdown file at a site's root, such as /llms.txt, that gives language models a short summary and a curated list of key pages. It is a community proposal from llmstxt.org, not an official standard, and it does not control crawling.
Related: Validate your llms.txt
llms-full.txt
An optional companion to llms.txt that contains the full text of a site's key documentation in a single Markdown file.
Related: llms.txt generator
O
OAI-SearchBot
OpenAI's crawler for ChatGPT search. Allowing it in robots.txt lets pages be shown and linked in ChatGPT search results.
Related: Check OAI-SearchBot access
P
PerplexityBot
The crawler Perplexity uses to index websites so they can be surfaced and linked in its answers. Perplexity states it is not used to train foundation models.
Related: Check PerplexityBot access
Q
Query fan-out
A technique in which an AI search system splits one question into several related sub-queries, retrieves results for each and combines them into an answer. Pages that cover a topic thoroughly can match more of those sub-queries.
R
RAG (Retrieval-Augmented Generation)
A method in which a system retrieves relevant documents first and then has a language model write an answer from them. Most AI search products use a form of RAG, which is why crawlability and clear content matter.
robots.txt
A plain text file at a site's root that tells crawlers which paths they may or may not access, using User-agent groups with Allow and Disallow rules. It is standardised in RFC 9309 and is voluntary for crawlers to follow.
Related: Test your robots.txt
S
sameAs
A Schema.org property that links an entity to its official profiles elsewhere, such as Wikipedia, Wikidata, LinkedIn or social accounts, helping machines confirm that they all describe the same organisation or person.
Schema.org
A shared vocabulary of types and properties, such as Organization, Product, Article and FAQPage, used to write structured data that search engines and other systems understand.
Related: Generate schema
Structured data
Machine readable information added to a page, usually as JSON-LD, that explicitly describes its entities and content. It can enable rich results and makes facts easier for AI systems to parse.
T
Topical authority
The depth and breadth with which a site covers a subject, through many connected, useful pages. It helps search engines and AI systems treat the site as a reliable source on that topic.
Z
Zero-click search
A search that ends without a click to any website because the answer is shown directly in the results, an AI Overview or an AI chat response. Being the cited source becomes the main way to earn visibility.
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