THE TOOLKIT
Appendix D — Glossary
Plain-language definitions for the terms used throughout the book: AEO and GEO, chunking, citation rate, mention rate, recommendation rate, query fan-out, grounding, retrieval-augmented generation and the rest. Written so a non-specialist stakeholder can read a report without a translator sitting next to them.
From Becoming the Answer by Jeremy Osborn · 278 words
AEO / GEO — Answer engine optimization, generative engine optimization. Used interchangeably. The practice of getting a brand included and well-positioned in AI-generated answers.
Chunk — A segment of a document, typically a few hundred tokens, indexed independently. The actual unit of retrieval.
Citation rate — Share of tracked questions where your domain appears as a source. Different from mention rate.
Entity — A specific, identifiable thing — a company, person, product — that a knowledge graph can resolve and attach facts to.
Ghost citation — An appearance where your site is cited as a source but your brand is never named in the answer. Roughly 62 percent of appearances.
Grounding — Checking generated claims against retrieved sources. Produces support scores, and can suppress low-confidence output entirely.
Information gain — What a passage offers that the passage it’s compared against does not. The one content principle that survives the evidence.
Mention rate — Share of tracked questions where your brand is named in the answer. The recommendation metric.
Query fan-out — Breaking one question into several sub-questions run in parallel. Confirmed by Google; the number of sub-questions is not public.
RAG — Retrieval-augmented generation. Retrieve relevant passages, put them in the model’s context, generate an answer grounded in them.
Retrieval threshold — The score below which a system answers from its own knowledge without searching. Google’s documented default is 0.3.
Share of voice — How often and how prominently a brand appears in AI answers relative to competitors. Widely sold, rarely sampled adequately.
UCP / ACP / MCP / A2A — Universal Commerce Protocol (Google), Agentic Commerce Protocol (OpenAI and Stripe), Model Context Protocol (Anthropic-originated), Agent2Agent (Linux Foundation).