Glossary
The AI search vocabulary.
Every term you'll encounter in GEO, AEO, and LLMO — defined plainly.
- GEO
- Generative Engine Optimization. Optimizing content to be cited by AI systems (ChatGPT, Perplexity, Gemini) when they generate responses. Formally defined by Princeton researchers in November 2023. This is the primary brand term.
- AEO
- Answer Engine Optimization. Originally about featured snippets and voice search. Now repurposed to include AI-generated answers. Broader than GEO — covers featured snippets, voice assistants, and AI chat responses.
- LLMO
- Large Language Model Optimization. A technical subset of GEO focused on how LLMs retrieve and cite content through training data and RAG pipelines. Functionally similar to GEO with a more technical framing.
- AIO
- AI Optimization / AI Overviews. Two meanings: (1) an umbrella term covering GEO + AEO + LLMO, or (2) Google's 'AI Overviews' summaries at the top of results. Context determines which is meant.
- AI SEO
- AI Search Engine Optimization. Two different meanings: (1) optimizing for AI search engines (same as GEO), or (2) using AI tools to do traditional SEO faster. Always ask which is meant.
- GXO
- Generative Experience Optimization. A newer term focused on the full user experience within an AI-generated answer, not just being cited. Less common but appearing in 2026 trend publications.
- AISO
- AI Search Optimization. Another synonym for GEO. Used by a handful of agencies but considered contested, with no clear distinct meaning.
- AI Citation
- A reference to your brand or content inside an AI-generated answer. The core unit of GEO success.
- Answer-First Content
- Content that leads each section with a direct, quotable statement before elaborating — the format AI engines extract most easily.
- Entity
- A distinct, identifiable thing (a company, person, or product) that AI systems recognize and track across the web.
- Knowledge Graph
- A structured map of entities and their relationships that search and AI systems use to understand the world.
- RAG
- Retrieval-Augmented Generation — when an AI model retrieves external documents at answer time and cites them. A key mechanism GEO targets.
- Schema Markup
- Structured data (JSON-LD) added to a page that helps search engines and AI models understand its meaning.
- Zero-Click Search
- A search that is answered directly on the results page or by an AI assistant, with no click through to a website.
- llms.txt
- An emerging file standard that gives AI systems a curated map of a site's most important content.