--- title: "AI Optimization Glossary & Comparisons — AIOvsSEO" description: "Plain-English definitions of GEO, AEO, AIO, llms.txt, Content-Signal, structured data, entity SEO, MCP, RAG and more — plus head-to-head comparisons of the key concepts." canonical: https://aiovsseo.com/glossary.html date: 2026-06-07 --- # The AI optimization glossary Plain-English definitions of the concepts behind GEO, AEO and AIO — and head-to-head comparisons of the ones people confuse most. ### AI Optimization (AIO) AI Optimization (AIO) is the practice of structuring your web presence so that AI engines — ChatGPT, Claude, Perplexity, Gemini an… ### Answer engine An answer engine is a system that responds to a query with a direct, synthesized answer rather than a list of links. Examples incl… ### AI Overview A Google AI Overview is the AI-generated summary that appears at the top of some search results, synthesizing an answer from multi… ### llms.txt llms.txt is a proposed Markdown file placed at a website’s root that describes the site and links to its key resources, helping AI… ### Content-Signal Content-Signal is an emerging robots.txt directive that lets a site separate three permissions: search indexing, AI retrieval (RAG… ### Structured data (JSON-LD) Structured data is machine-readable markup, usually JSON-LD using the Schema.org vocabulary, that describes a page’s content to en… ### Entity SEO Entity SEO is the practice of getting your brand, people or products recognized as distinct, trusted entities across the web and i… ### LLM citation An LLM citation is when an AI model names, links or attributes your content as a source in the answer it gives a user. It is disti… ### Model Context Protocol (MCP) The Model Context Protocol (MCP) is an open standard that lets AI assistants connect to external tools and data sources through a … ### Retrieval-augmented generation (RAG) Retrieval-augmented generation (RAG) is a technique where an AI model fetches relevant external documents at answer time and groun… ### E-E-A-T E-E-A-T stands for Experience, Expertise, Authoritativeness and Trustworthiness — the quality framework Google uses to assess cont… ### AI crawler An AI crawler is a bot run by an AI company to fetch web content for model training or live retrieval. Examples include GPTBot, Cl… ## Head-to-head comparisons ### GEO vs SEO GEO optimizes to be cited by generative engines; SEO optimizes to rank and be clicked. A clear comparison of goals, tactics, metri… ### AEO vs GEO AEO and GEO overlap heavily and are often used interchangeably. The useful distinction: GEO optimizes the content engines draw fro… ### AEO vs SEO SEO targets rankings and clicks; AEO targets being the synthesized answer an AI gives. Why AEO is a distinct discovery layer you c… ### llms.txt vs robots.txt robots.txt controls whether crawlers may access your content; llms.txt describes and links your content for AI agents. One is acce… ### AI Overviews vs Featured Snippets A featured snippet quotes one source verbatim in a box; an AI Overview generates a new answer synthesized from several cited sourc…