Home / Glossary

The AI visibility glossary

Plain-English definitions of the terms behind SEO, GEO and getting found by AI. No jargon, no fluff.

SEO Search Engine Optimization

SEO is the practice of optimizing a website to rank higher in traditional search engine results like Google. It works primarily through keywords, backlinks, technical site health and content quality.

SEO remains the foundation of online visibility. It targets the ranked list of blue links that has defined search for two decades. It still matters in 2026 — but it no longer covers how a growing share of people find information.

GEO Generative Engine Optimization

GEO is the practice of structuring content so generative AI systems such as ChatGPT, Claude, Gemini and Perplexity cite it as a source when they generate answers. Where SEO targets rankings, GEO targets being the cited answer itself.

GEO relies on different signals than SEO. Research shows brand mentions correlate far more strongly with AI citation than backlinks, and that answer-first structure, fact density and schema markup are the strongest levers. It is also called AEO, LLMO, GSO or AIO depending on who you ask.

AEO Answer Engine Optimization

AEO is the practice of optimizing content to become the direct answer surfaced by answer engines and AI Overviews. It overlaps heavily with GEO and uses structured data, FAQ formatting and concise answer blocks.

In practice, AEO and GEO are often used interchangeably. The industry has not yet settled on one term — what matters is the shared goal: being the answer, not just a link near it.

LLM Large Language Model

An LLM is an AI model trained on vast amounts of text to understand and generate human language. ChatGPT, Claude and Gemini are all powered by large language models.

LLMs are the engines behind the AI assistants your buyers now use to research products and services. Understanding how they select and cite sources is the core of GEO.

AI Overview

An AI Overview is an AI-generated summary shown at the top of Google search results that answers a query directly. It often satisfies the user without any click to an individual website.

AI Overviews already appear in a significant share of Google searches and are a major driver of the rise in zero-click behaviour. Being cited inside them is a key AEO objective.

Citation Rate

Citation rate is the frequency with which an AI system names or links to a specific brand or source when answering relevant prompts. It is the core success metric of GEO, replacing click-through rate as the number that matters.

Tracking citation rate across ChatGPT, Claude, Gemini and Perplexity tells you whether your AI visibility is improving — in a way that traditional rank tracking cannot.

Share of Voice

Share of voice in AI is the proportion of relevant AI answers where your brand is cited compared to competitors. If AI names a competitor in eight of ten answers and you in two, your share of voice is 20%.

It reframes competition: the goal is not just to be cited, but to be cited more often than the alternatives buyers are considering.

Zero-Click Search

A zero-click search is one answered directly on the results page or by an AI, so the user never clicks through to a website. Over half of Google searches now end this way.

Zero-click behaviour is why visibility is shifting from traffic to citation. If users get their answer without clicking, being named in that answer becomes the only form of presence that counts.

Agentic AI

Agentic AI refers to AI systems that take actions and complete multi-step tasks autonomously on a user's behalf — including researching, shortlisting and even purchasing products or services without step-by-step human direction.

As buying research moves to AI agents, brands will need to be machine-readable and citable to be considered at all. This is widely seen as the next frontier of visibility beyond today's chat-based search.

World Model

A world model is an AI system's internal representation of how the world works, allowing it to reason, predict and plan rather than only generate plausible text. It is a step toward AI that understands context rather than just patterns.

For marketers, world models point to a future where AI evaluates brands on deeper, more contextual understanding — making genuine authority and accurate information more important than surface-level optimization.

Answer Capsule

An answer capsule is a concise 40 to 60 word direct answer placed immediately under a question-format heading, written specifically so AI systems can extract and cite it in full.

Audits of high-traffic domains found answer capsules to be the single strongest predictor of ChatGPT citations. Every well-optimized section should open with one.

RAG Retrieval-Augmented Generation

RAG is a technique where an AI retrieves live information from a search index before generating its answer. ChatGPT's web search uses RAG via Bing's index, which is why being indexed by Bing matters for AI visibility.

Understanding RAG explains a key GEO tactic: to be cited by ChatGPT, your content must be retrievable in the index it pulls from — not just live on your site.

Schema Markup JSON-LD

Schema markup is structured data added to a page's HTML that explicitly describes its content to search engines and AI crawlers. Pages with schema markup are significantly more likely to be cited by AI systems.

It must be inline in the HTML source. AI crawlers like GPTBot and ClaudeBot typically do not execute JavaScript, so schema rendered client-side is invisible to them — a common and costly mistake.

llms.txt

llms.txt is an emerging text file standard placed at a website's root that guides AI crawlers to the site's most important content, similar to how robots.txt guides search engines.

It is not yet universally adopted, but implementing it early is low-cost and positions a site ahead of the standard becoming essential.

Want to know your citation rate?

A free mini-audit shows where you stand across ChatGPT, Claude, Gemini and Perplexity.

Get your free audit →