The SEO glossary for buyers
Short, sourced definitions of the terms that come up when you buy search work: SEO, GEO and AI search, conversion rate optimization, analytics and the platforms your site runs on. Each entry opens on a plain answer, says why it matters to you, and links to the deeper guide.
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Search has picked up a second vocabulary in two years. The old one, rankings, backlinks, Core Web Vitals, never went away, and a new one arrived on top of it: AI Overviews, AI Mode, query fan-out, citations, GEO. Proposals mix the two freely, and it is hard to judge a plan when half of its nouns are unfamiliar.
This glossary is the reference we wish buyers had before a sales call. Every entry opens on a definition short enough to read in one breath, then says two things a generic dictionary does not: why the term should matter to someone paying for the work, and how it is actually measured or applied. Where a claim rests on a search engine's documentation or a piece of research, the source is listed at the foot of the entry.
How is the glossary organised?
Alphabetically, with a filter for five areas: SEO, GEO and AI search, conversion rate optimization, analytics, and the platforms sites are built on. Terms link to their neighbours, so an entry on AI Overviews points on to query fan-out and zero-click searches, and each one links down to the longer guide on the blog when that guide is live.
What will you not find here?
Invented numbers. Where a figure appears it comes from the named source. We also leave out jargon that exists only to sell a tool, and we say plainly when a term is overhyped, as the entry on llms.txt does.
A
- AI citation
- An AI citation is a link or named source that an AI assistant attaches to its answer to show where a statement came from.
- AI crawler
- An AI crawler is an automated bot run by an AI company to fetch web pages, either to build a search index its assistant retrieves from, to fetch a page a user has asked about, or to collect training data.
- AI hallucination
- An AI hallucination is a confident, fluent statement an AI model produces that is factually wrong, made up, or not actually supported by the sources it cites.
- AI visibility
- AI visibility is how often, how accurately and how favourably a brand appears in the answers AI assistants and AI-powered search features give to relevant buyer questions, whether as a citation, an unlinked mention, or a recommendation.
- Answer engine
- An answer engine is a search tool, such as ChatGPT, Perplexity, Claude or Google's AI Overviews, that responds to a query with a direct, synthesised answer written in natural language rather than a list of links a person has to click through and read themselves to find the answer.
- Answer engine optimization (AEO)
- Answer engine optimization (AEO) is the practice of structuring content so that search features and AI assistants can lift a direct answer from it, whether that answer appears as a featured snippet, a voice assistant reply, a People Also Ask box or a cited sentence inside an AI-generated summary.
C
- ChatGPT search
- ChatGPT search is the web search capability built into ChatGPT that lets it look up current information and cite sources when answering a query, rather than relying only on what it learned during training.
- Content chunking
- Content chunking is splitting a longer document into smaller, self-contained sections before it is indexed for AI retrieval, so a system can fetch and cite the specific passage that answers a question instead of returning an entire page.
E
- Entity (search)
- An entity is a specific, uniquely identifiable thing, a person, organisation, place or product, that a search engine or AI model represents as a distinct concept in its knowledge base, connected to related facts and other entities, rather than as just a string of matching text on a page.
G
- Generative engine optimization (GEO)
- Generative engine optimization (GEO) is the work of making a brand's pages and facts easy for AI answer engines such as ChatGPT, Perplexity, Claude, Gemini and Google's AI Overviews to find, understand and cite, so the brand is named and linked when a buyer asks an assistant for a recommendation or an explanation.
- Google AI Mode
- Google AI Mode is a conversational search experience inside Google Search that answers a question with an AI-generated response, lets the user ask follow-ups, and cites web pages as sources.
- Google AI Overviews
- Google AI Overviews are AI-generated summaries that appear at the top of some Google results pages, answering the query in a few paragraphs and linking to the web pages the summary drew on.
- Google-Extended (robots token)
- Google-Extended is a robots.txt token that lets a site block its content from being used to train future Gemini and Vertex AI generative models, separately from Googlebot.
- GPTBot
- GPTBot is the crawler OpenAI uses to collect publicly available web content to help train and improve its AI models.
- Grounding (AI search)
- Grounding is connecting an AI model's response to real, current external sources, usually live search results, at the moment it answers, rather than relying only on facts it memorised during training.
K
- Knowledge Graph
- The Knowledge Graph is Google's database of entities, meaning people, organisations, places and things, together with the facts about them and how they relate.
- Knowledge panel
- A knowledge panel is the information box, usually on the right side of Google's desktop search results, that summarises facts about a recognised entity, such as a company, person or place, pulled from the Knowledge Graph, Google Business Profile and other verified or widely corroborated sources.
L
- Large language model (LLM)
- A large language model is an AI system trained on huge amounts of text to predict and generate human-like language.
- LLM optimization (LLMO)
- LLM optimization (LLMO) is the effort to influence how large language models describe and recommend a brand, both in answers generated from live web retrieval and in what a model has absorbed from its training data.
- llms.txt file
- An llms.txt file is a proposed plain-text Markdown file placed at a site's root that gives language models a short summary of the site and links to its most useful pages.
O
- OAI-SearchBot
- OAI-SearchBot is the crawler OpenAI uses specifically to build the search index that powers ChatGPT search results and citations.
P
- Parametric knowledge
- Parametric knowledge is the factual and linguistic knowledge an AI model has encoded internally in its parameters during training, as opposed to knowledge it retrieves live from an external source at the moment it answers.
- Prompt tracking
- Prompt tracking is running a consistent, defined set of realistic buyer questions against AI assistants on a recurring schedule and recording how a brand appears in each answer, whether it is cited, merely mentioned, or absent entirely, and how that compares to competitors named in the same answers.
Q
- Query fan-out (AI Mode)
- Query fan-out is the technique AI search systems such as Google AI Mode use to answer a question: the system breaks the question into related sub-questions, runs many searches for them at the same time, and combines what it retrieves into one answer with citations from several pages.
R
- Retrieval-augmented generation (RAG)
- Retrieval-augmented generation (RAG) is a method in which a language model first retrieves relevant documents from a search index or database and then writes its answer using those documents, rather than relying only on what it learned in training.
U
- Unlinked brand mention
- An unlinked brand mention is an instance of a business's name appearing on another website, or in an AI assistant's answer, without a hyperlink back to the business's own site.
V
- Vector embedding
- A vector embedding is a list of numbers that represents the meaning of a piece of text, image or other content, positioned in a mathematical space where content with similar meaning sits close together.
W
- Wikidata
- Wikidata is a free, structured, machine-readable knowledge base run by the Wikimedia Foundation that stores facts about entities, people, organisations, places and products, as linked data.
Questions we get asked
Who writes these definitions?
The two founders, Ibrahem Helal and Jeremy Zava, write and review every entry. Each one names at least one source you can check, usually the search engine's own documentation or the original research, so you are not taking a definition on our word alone.
Why does every entry open with a short paragraph?
Because that paragraph is the answer. It is written to make sense on its own in forty to sixty words, which is also the shape search features and AI assistants quote. The rest of the entry says why the term matters to a buyer and how it is measured or applied.
What is the difference between SEO, GEO and AEO?
SEO gets pages ranked in search results. GEO gets a brand named and cited in answers from assistants such as ChatGPT, Perplexity, Claude and Google's AI features. AEO is the older label for structuring answers so search features can lift them. The work overlaps heavily, and each has its own entry here.
How often are new terms added?
Two a day from 24 September 2026 until the planned list of 120 terms is complete, then as new terms enter common use. Entries are updated when the underlying documentation changes, and the date on each entry says when that last happened.
Can I quote or link to a definition?
Yes. Link to the entry's own page so readers get the source list with it. If a definition is wrong or out of date, email us and we will correct it and change the date on the entry.
Do you sell every service described here?
No. The glossary covers terms buyers meet whoever they hire. Where we do the work, the entry links to the service page; where we do not, it says what the term means and stops there.
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30 minutes. No pitch deck. You leave with a prioritised plan.