Glossary

AEO, GEO and AI search glossary

The AI search world invented a new vocabulary faster than anyone could keep up. These are 30 plain-English definitions of the terms that actually matter, each one grounded in the docs, including Google's official AI optimization guide. We wrote them the way an answer engine likes to quote: “a clear definition, then why it matters, then what to do.”

The discipline and its names

• What is answer engine optimization (AEO)? Earning the answer, not just the link.
• What is generative engine optimization (GEO)? Being the source an AI quotes and cites.
• What is LLMO (large language model optimization)? Same discipline, model-flavored name.
• What is AIO (AI optimization)? Two meanings, one acronym. We define both.

How AI search works

• What is RAG (retrieval-augmented generation)? How AI answers from documents it retrieves.
• What is query fan-out? One question becomes many searches behind the scenes.
• What are Google AI Overviews? Google's AI answers at the top of the results page.
• What is Google AI Mode? Google's conversational, fully AI search experience.
• What is agentic search? When an AI agent does the searching for the user.
• What is MCP (Model Context Protocol)? The plug standard that connects AI agents to tools.
• What is Perplexity Pages? Perplexity's publishing feature, currently retired mid-rebuild.
• What is zero-click search? The answer appears, the click never happens.
• What is the great decoupling? Impressions rise while clicks fall.
• What is AI share of voice? How often the machines mention you.

The AI crawlers

• What is OAI-SearchBot? OpenAI's crawler that earns you a ChatGPT citation.
• What is GPTBot? OpenAI's training crawler. Not the citation bot.
• What is PerplexityBot? Perplexity's crawler for cited sources.
• What is Claude-SearchBot? Anthropic's search crawler that earns Claude citations.
• What is Google-Extended? The robots.txt token that controls Gemini training use.
• What is llms.txt? A proposed AI index file. Not a Google standard.

Ranking and quality

• What is E-E-A-T? How Google judges who to believe.
• What is helpful content? Write for people first, machines follow.
• What is topical authority? Depth across a topic beats one keyword page.
• What is passage indexing? Ranking one passage, not the whole page.
• What is a featured snippet? The answer Google lifts to position zero.

Entities and schema

• What is entity SEO? Engines rank things, not just keywords.
• What is sameAs schema? Linking your profiles so a machine knows it's you.
• What is a Wikidata QID? A permanent ID that names your entity.
• What is a knowledge panel? The box that proves Google knows who you are.
• What is a brand SERP? The results page for your own name. Your business card.

Where this fits

These terms run through our two pillars, what is AEO and what is GEO, and the Fix Library that turns them into action. To see which of these concepts your own site is getting wrong, run the free preview with our AEO checker or the full audit at the app.