# GEO glossary

Short, working definitions for the vocabulary used in generative engine optimization. Each entry explains what the term means in practice, not just what the acronym expands to.

## GEO — generative engine optimization

The practice of making a brand discoverable, quotable and accurately described in AI-generated answers. It covers crawler access, content structure, corroboration and measurement. GEO is a superset of tactics, not a single technique.

## AEO — answer engine optimization

Often used interchangeably with GEO. In practice, AEO emphasizes winning featured answers and direct-response formats; GEO emphasizes presence across generated, multi-source answers. The overlap is large and the distinction is mostly vendor vocabulary.

## AI visibility

Whether your brand appears in AI answers for the questions your buyers ask. It is usually reported as a rate — the share of tested prompts where you are mentioned.

## Mention rate

The percentage of sampled prompts where your brand is named. A mention is any appearance of the brand name in the answer text, regardless of whether the answer recommends you.

## Citation rate

The percentage of sampled prompts where your domain is used as a source and linked. Citation is stricter than mention: a brand can be named without being cited, and cited pages drive traffic while bare mentions do not.

## Share of voice (SoV)

Your brand mentions divided by all brand mentions in the category, across the same prompt set. Requires an explicit competitor list and a stable prompt set to be comparable.

## Prompt set / prompt panel

The fixed list of questions sampled on a schedule. A prompt set is the measuring instrument; changing it invalidates trend comparisons unless the change is versioned.

## AI crawler / AI bot

A program operated by an AI provider that fetches pages for retrieval or training. Common user agents: `GPTBot`, `OAI-SearchBot`, `ChatGPT-User`, `ClaudeBot`, `PerplexityBot`, `Google-Extended`, `CCBot`, `Bingbot`, `Applebot-Extended`.

## GPTBot

OpenAI's crawler for training and index building. Blocking it removes your site from that evidence set. `OAI-SearchBot` handles search-index crawling and `ChatGPT-User` handles user-initiated fetches; the three have different roles and are often configured separately.

## Google-Extended

A `robots.txt` token that controls whether Google's Gemini and Vertex AI products may use your content, separate from Google Search indexing. Allowing it is a decision about AI visibility versus content control, not an SEO setting.

## CCBot

Common Crawl's crawler. Its corpus feeds many downstream datasets, so blocking it can affect models you do not directly interact with.

## llms.txt

A community-proposed Markdown file at `/llms.txt` summarizing a site for language models: brand description, product facts, key URLs. Not a formal standard and not a confirmed ranking factor; useful as a canonical fact sheet and crawl guide.

## llms-full.txt

An extended variant containing fuller page text rather than only summaries. Adoption is lower than `llms.txt`.

## AI Overviews

Google's generated summary shown above some search results, with citations to source pages. It is one AI surface among several; ranking well organically improves the odds of being cited there.

## Grounding / retrieval

The mechanism by which a model pulls external sources into an answer. Without retrieval, an answer relies only on parametric memory, which is where stale and wrong brand facts usually originate.

## Parametric memory

Facts a model absorbed during training. It cannot be updated by editing your site; the only path is better corroborated public information and retrieval-based answers.

## Hallucination

A confident but incorrect statement. In GEO the relevant form is brand hallucination: wrong pricing, wrong product scope, wrong headquarters.

## Claim accuracy / fact verification

Checking the factual statements AI makes about your brand against your own published facts. Distinct from mention counting — it catches "AI says we charge $99" errors.

## Sentiment

Whether an AI answer describes your brand positively, neutrally or negatively. Useful as a trend; unreliable as a precise score because generated language is non-deterministic.

## AI referral traffic

Visits to your site where the referrer is an AI platform. Measured in analytics; a lower bound because many AI-originated visits arrive without a referrer.

## Agent-ready content

Content structured so autonomous agents can parse and act on it: stable URLs, clean HTML, explicit facts, machine-readable summaries.

## Schema markup / structured data

JSON-LD annotations that describe entities and relationships to machines. It exposes facts you already publish; it does not create new ones.

## Non-determinism

The property that the same prompt can produce different answers across runs. It is the main reason GEO measurement needs repeated sampling rather than single tests.

## Related reading

- [What is generative engine optimization?](/guides/what-is-generative-engine-optimization)
- [What is AI share of voice?](/answers/what-is-ai-share-of-voice)
- [Do I need an llms.txt file?](/answers/do-i-need-llms-txt)
- [Best GEO tools](/compare/best-geo-tools)