AI search has minted a vocabulary faster than anyone can keep up with it. Here's every term that actually matters — each defined in plain English, in two or three sentences you can quote.
Bookmark this page. We keep it current as the language evolves, and we link to the deeper pieces — like why GEO matters and the eight-step playbook — where a definition deserves a full article.
Generative Engine Optimization (GEO)
Generative Engine Optimization is the practice of optimizing a brand and its content to be cited, quoted, and recommended by AI engines such as ChatGPT, Perplexity, and Google AI Overviews. Where classic SEO competes for position in a list of links, GEO competes for a place inside the answer itself.
Answer Engine Optimization (AEO)
Answer Engine Optimization is the practice of structuring content so that search and AI systems can extract a direct answer from it. The term is largely synonymous with GEO; AEO emphasizes the answer-first formatting, GEO the generative engines consuming it.
Answer engine
An answer engine is a system that responds to a query with a synthesized answer rather than a list of links — ChatGPT, Perplexity, Copilot, and Google's AI Overviews are all answer engines. The shift from search engine to answer engine is what makes GEO necessary.
AI Overviews
AI Overviews are the AI-generated summaries Google shows at the top of many search results pages, with citations linking to the sources used. Appearing in an AI Overview — as a cited source or a named brand — is now the most visible position in Google search.
AI citation
An AI citation is a reference to a brand or page inside an AI-generated answer — either a named mention ("Jumpstart, an Alexandria-based agency…") or a linked source. Citations are the core currency of GEO: they're what rankings were to classic SEO.
Citation share
Citation share is the percentage of relevant AI answers in which a brand appears, measured across a tracked set of customer questions. Tracking citation share over time is how you know whether GEO work is paying off.
Entity
An entity is a distinct, known thing — a business, person, place, or concept — that search and AI systems recognize and store facts about, independent of any keyword. Engines cite brands they can confidently identify as entities.
Entity SEO
Entity SEO is the work of making an engine's model of who you are strong and consistent: coherent Organization schema, a clear About page, matching name and contact details everywhere you appear, and presence on the platforms that define your category.
Knowledge Graph
The Knowledge Graph is Google's database of entities and the relationships between them. AI Overviews and other Google surfaces draw facts from it directly, which is why claiming your Google Business Profile and keeping your details consistent feeds straight into AI visibility.
Structured data (schema markup)
Structured data is machine-readable code — usually JSON-LD using the schema.org vocabulary — added to a page to state unambiguously what the page and the business are: Organization, FAQPage, Article, Service, and so on. It hands engines a clean version of your facts instead of making them infer.
llms.txt
llms.txt is a plain-markdown file at a site's root that gives AI systems a concise, curated summary of the site and links to its most important pages. Think of it as robots.txt's younger sibling: robots.txt says what bots may crawl, llms.txt tells them what matters. (Here's ours.)
AI crawler
An AI crawler is a bot that fetches web pages for an AI system — for model training, for live search retrieval, or both. Examples include OpenAI's GPTBot, Anthropic's ClaudeBot, and PerplexityBot. Sites control access through robots.txt; blocking them means opting out of AI answers.
Topical authority
Topical authority is the credibility a site earns by covering a subject comprehensively — the core concept, the comparisons, the edge cases, the how-tos — in interlinked content rather than isolated pages. Engines cite sources that demonstrably know the whole territory, not just one corner of it.
Topic cluster
A topic cluster is a group of interlinked pages covering one subject: a central pillar page plus supporting articles that each answer a specific sub-question and link back to the pillar. Clusters are how topical authority gets built deliberately instead of accidentally.
E-E-A-T
E-E-A-T stands for Experience, Expertise, Authoritativeness, and Trustworthiness — the qualities Google's quality guidelines use to judge whether content and its author deserve to be believed and surfaced. AI engines apply the same instinct: they quote sources that look credible and verifiable.
Retrieval-augmented generation (RAG)
Retrieval-augmented generation is how AI search works under the hood: the system first retrieves relevant passages from the web, then writes its answer from what it found. GEO is, in practice, optimization for the retrieval step — being the passage the engine finds and trusts enough to quote.
Extractable passage
An extractable passage is a paragraph that makes complete sense on its own — terms defined in place, no "as discussed above" — so an AI engine can lift it directly into an answer. Writing in extractable passages is step two of our GEO playbook.
Inverted pyramid
The inverted pyramid is a writing structure that puts the direct, complete answer in the first one or two sentences, with nuance and supporting detail below. Journalists use it to survive editors' cuts; GEO uses it because engines extract from the top.
Zero-click search
A zero-click search is one that ends on the results page: the user gets their answer from an AI summary or featured snippet and never visits a website. As zero-click grows, being named inside the answer matters as much as ranking beneath it.
NAP consistency
NAP consistency means a business's Name, Address, and Phone number are identical everywhere they appear — your website, Google Business Profile, directories, and social profiles. Mismatched details erode an engine's confidence in your entity, and unconfident engines don't cite.
Digital PR
Digital PR is earning mentions, links, and citations from credible third-party publications — industry press, expert roundups, local media. AI engines weigh this independent corroboration heavily: what others say about you counts for more than what you say about yourself.
IndexNow
IndexNow is an open protocol that lets a website instantly notify participating search engines — including Bing, whose index feeds Microsoft Copilot and DuckDuckGo — the moment a page is added or updated, instead of waiting to be recrawled. Faster indexing means fresher facts in AI answers.
Want the strategy, not just the vocabulary?
Definitions are the map; execution is the territory. Start with why AI search is the new front page, then work through the eight-step playbook we run for clients — or skip ahead and let us run it for you.