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AI Search & LLM SEO Glossary

30+ terms defined, plain English. The category itself is new - most teams need shared vocabulary before they can ship a program.

Track your AI visibility
Core conceptsSurfaces & platformsSignals & rankingMeasurementCrawlers & infrastructure
4 terms

Core concepts

AEO

Answer Engine Optimization

Optimizing content so answer engines (Perplexity, Google AI Overviews, ChatGPT Search) quote it as the direct answer to a query.

AI search optimization

The umbrella term for optimizing for any AI-powered search surface - including ChatGPT Search, Perplexity, Google AI Overviews, and AI Mode.

GEO

Generative Engine Optimization

The practice of optimizing brand and content so generative AI engines (ChatGPT, Perplexity, Gemini, Claude, Grok) mention, recommend, and cite you.

LLM SEO

Optimizing for Large Language Models - making sure ChatGPT, Claude, Gemini, Perplexity, and Grok know about, cite, and recommend your brand.

7 terms

Surfaces & platforms

AI Mode

Google's full conversational search experience - an alternative to classic SERPs where AI answers the query end-to-end.

AI Overviews

Google's generative-AI answer box at the top of search results, powered by Gemini. Now appears for more than half of qualifying US queries.

ChatGPT Search

OpenAI's live-retrieval mode inside ChatGPT - pulls real-time web results, cites them, and answers in the chat surface.

Claude

Anthropic's LLM family (Opus, Sonnet, Haiku). Available via Claude.ai, the Anthropic API, and embedded in Notion, Slack, Quora, Cursor, and more.

Gemini

Google's multimodal LLM family. Powers Gemini app, AI Overviews, AI Mode, Workspace AI, and the Vertex AI / AI Studio APIs.

Grok

xAI's LLM, with native access to real-time X (formerly Twitter) data. Powers Grok-on-X and Grok.com.

Perplexity

A dedicated answer engine that retrieves the web in real time and synthesises answers with inline citations.

6 terms

Signals & ranking

Cross-source consensus

How consistently many independent sources describe a brand the same way. The single biggest factor in whether an LLM names a brand by default.

Extractability

How easily an LLM can lift a clean, summarisable answer from your page. High extractability dramatically increases citation rate on grounded surfaces.

Grounding

Augmenting an LLM's answer with retrieved evidence so the model can cite verifiable sources, rather than relying on training memory alone.

RAG

Retrieval-Augmented Generation

A technique where an LLM retrieves external documents at inference time and uses them to ground its answer. Powers Perplexity, ChatGPT Search, and AI Overviews.

Schema (structured data)

JSON-LD or microdata that labels your content for machines. FAQ, Article, Product, HowTo, and Organization schema all improve LLM extractability.

Training corpus

The dataset an LLM was trained on. Brands that appear frequently and consistently in the training corpus are recalled by name in answers, with no live retrieval required.

6 terms

Measurement

Citation share

Percentage of cited sources in an LLM answer that come from your domain. Only meaningful on grounded surfaces (Perplexity, ChatGPT Search, AI Overviews).

Mention rate

The percentage of prompts in a defined panel where an LLM names your brand. The headline metric of LLM SEO programs.

Rank in answer

Where your brand appears in an LLM's ordered recommendation set - first paragraph (best), middle, or final mention (weakest).

Sentiment (in LLM answers)

The tone with which an LLM describes your brand - positive, neutral, negative - when it does mention you.

Share of voice (AI)

Your mention rate as a percentage of the total mentions of you plus your named competitors across LLM answers.

Zero-click search

Searches that end inside the search surface without a click to an external site. Now 58% of US searches.

7 terms

Crawlers & infrastructure

ClaudeBot

Anthropic's web crawler for Claude training and (in some configurations) retrieval.

Google-Extended

An opt-in agent that lets Google use your content for Gemini training. Separate from Googlebot, which is required for classic search.

GPTBot

OpenAI's crawler for ChatGPT training data. Identified by the user agent "GPTBot".

llms.txt

A proposed standard file at the root of a site that tells LLM crawlers what content is available, in what format, and how to use it.

OAI-SearchBot

OpenAI's live-retrieval crawler for ChatGPT Search. Separate from GPTBot and must be allowed independently.

PerplexityBot

Perplexity's live-retrieval crawler. Blocking it removes you from Perplexity citations.

robots.txt

The decades-old file telling web crawlers what they can fetch. Used to allow or block GPTBot, ClaudeBot, PerplexityBot, Google-Extended, and others.

Why this glossary exists

AI search is a new category and the language is still settling. Two teams will use "GEO", "AEO", and "LLM SEO" for slightly different things; vendors will pick whichever sounds best in a deck. This glossary picks one definition for each term and sticks with it, so internal conversations and external content stop talking past each other.

Suggestions or corrections: [email protected].

Apply the vocabulary

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