AI search + SEO glossary

AI Overview (AIO) is Google's generative-AI answer panel that appears above blue-link results on Search, composed by Gemini 3 using retrieval-augmented generation over the same Google Search index.

Generative Engine Optimization (GEO) is the practice of optimizing brand visibility within AI search engines like ChatGPT, Google AI Overview, Gemini, Claude, and Perplexity, alongside (not instead of) traditional SEO.

The four-index reality is the structural fact that AI search isn't a single discipline because five major AI search engines source from four distinct underlying indexes — Google (for AIO + Gemini), Bing (for ChatGPT), Brave (for Claude), and Perplexity's own crawler.

Citation rate is the percentage of AI search responses (across queries, platforms, or personas) in which a brand is mentioned, recommended, or linked — the foundational visibility metric for Generative Engine Optimization.

Share of voice in AI search is the percentage of total brand mentions within an AI engine's response set that belong to one specific brand — a competitive measurement complementing the absolute citation rate.

Answer Engine Optimization (AEO) is the practice of structuring content so generative AI engines lift it directly into their answers — interchangeable with GEO as a label, distinguished from classic SEO by its focus on citation context rather than blue-link rank.

The Brave Search index is the independent web index maintained by Brave Software that Claude uses for real-time grounding via Brave's search API — smaller and more recency-biased than Google or Bing, making it the highest-leverage index for content-investment lift in the four-index reality.

AI Mode is Google's standalone chatbot-style AI search product — a full-page conversational interface that replaces traditional SERPs entirely, distinct from AI Overview which is the answer panel embedded above classic blue-link results.

Brand Radar is a persona-anchored, multi-platform brand-mention tracking discipline for AI search — measuring citation rate, share of voice, and citation context for a brand across ChatGPT, Google AI Overview, Gemini, Claude, and Perplexity simultaneously, distinct from social brand monitoring tools that watch X/Reddit/news mentions.

Citation position is the rank at which a brand appears in an AI engine's ordered list of recommendations within a response — first named, second, third — distinct from blue-link SERP rank and materially different from a passing mention in the answer body.

A knowledge graph is a structured representation of entities (people, products, places, concepts) and their relationships — the data layer Google + LLMs use to disambiguate brand mentions, ground generative answers, and decide which sources to cite.

An answer engine is a search system that synthesizes a direct answer from multiple sources instead of returning a list of links — ChatGPT search, Perplexity, Google AI Overview, and Claude with web search are the canonical examples.

Anti-prime queries are AI search measurement prompts that deliberately avoid naming the brand or product category in question — measuring organic surface in JTBD language instead of priming the model with the answer.

Persona-anchored measurement runs the same query set across multiple buyer ICPs simultaneously — revealing how AI engines route the same brand differently depending on the persona the model assumes is asking.

A cross-brand pattern is an AI search measurement finding that replicates across two or more independent brand audits — converting a single-brand observation from anecdote to structural evidence about how AI engines route queries.

Wedge visibility is the rate at which AI search responses surface a brand's signature differentiator — its single most important positioning claim — when the brand is named in the answer, regardless of which underlying engine or query type produced the response.

Surface rate is the percentage of AI search queries in which a brand is mentioned at all — the most basic AI visibility metric, and the one that saturates fastest for established brands.

Query priming is the effect where naming a brand, product, or category in an AI search prompt biases the model toward returning it — inflating measured visibility relative to what real, unprimed buyers would see.

Structured data is machine-readable markup (typically schema.org vocabulary in JSON-LD format) that describes the content and meaning of a webpage to search engines and AI systems — required for rich SERP features, helpful but not required for AI Overview citation per Google's 2026-05-15 guide.

JSON-LD (JSON for Linked Data) is the W3C-standard serialization format for embedding structured data in HTML pages — a JSON object wrapped in a script tag that declares schema.org vocabulary describing the page's content and entities.

E-E-A-T (Experience, Expertise, Authoritativeness, Trustworthiness) is Google's quality framework for evaluating content and the people behind it — added the second 'E' for Experience in 2022, and is a primary input to both classic Google ranking and AI Overview citation selection per Google's 2026-05-15 guide.

GPTBot is OpenAI's web crawler for training data collection, identifiable by the User-Agent string 'GPTBot/1.x' and the published IP range at openai.com/gptbot — distinct from OAI-SearchBot which fetches pages for real-time ChatGPT search citations.

PerplexityBot is Perplexity AI's web crawler that uniquely feeds both training data and Perplexity's live retrieval index in the same crawl event — a dual-horizon bot whose single visit produces both immediate citation visibility and long-term ranking compound.

ClaudeBot is Anthropic's web crawler that collects public content for Claude model training, identifiable by the User-Agent string 'ClaudeBot/1.0' and operating from Google Cloud Platform infrastructure with no published static IP range.

Google-Extended is a robots.txt directive that lets site owners opt out of Google's generative-AI training (Gemini + Vertex AI) without affecting Google Search ranking or AI Overview citation — a control token, not a crawler with its own User-Agent.

OAI-SearchBot is OpenAI's web-search crawler that fetches pages for real-time ChatGPT search citations — distinct from GPTBot (which collects training data) and from ChatGPT-User (which fetches user-pasted URLs), and the bot to allow if you want ChatGPT to cite your site.

llms.txt is a proposed AI search standard — a markdown file at the root of a domain that provides curated metadata about the site to AI systems — respected by Anthropic, Perplexity, and OpenAI's GPTBot but explicitly declined by Google as of 2026-05-15.

A rank tracker is a tool that performs daily SERP position lookups for a defined set of tracked keywords — and in 2026, AI-search-aware rank trackers must also track AI Overview, Gemini, and ChatGPT citation positions alongside traditional blue-link rank.

An MCP (Model Context Protocol) server exposes structured tools to LLM clients (Claude Desktop, Claude Code, Cursor, ChatGPT) over a JSON-RPC 2.0 transport — letting the model call your product's operations directly inside a chat session.