Reference

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.

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AI Optimization (AIO)

AI Optimization (AIO) is the practice of structuring your web presence so that AI engines — ChatGPT, Claude, Perplexity, Gemini an…

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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…

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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…

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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…

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Content-Signal

Content-Signal is an emerging robots.txt directive that lets a site separate three permissions: search indexing, AI retrieval (RAG…

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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…

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Entity SEO

Entity SEO is the practice of getting your brand, people or products recognized as distinct, trusted entities across the web and i…

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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…

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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 …

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Retrieval-augmented generation (RAG)

Retrieval-augmented generation (RAG) is a technique where an AI model fetches relevant external documents at answer time and groun…

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E-E-A-T

E-E-A-T stands for Experience, Expertise, Authoritativeness and Trustworthiness — the quality framework Google uses to assess cont…

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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