The SEO & AI Search Glossary
Every term defined in 60 words or less — precise enough for humans, extractable enough for machines. Yes, that's deliberate.
Last updated: · Reviewed quarterly
Definitions, the Way Machines and Humans Both Like Them
This glossary defines the vocabulary of modern search — classic SEO through GEO, AEO, and LLM-EEAT — in concise, self-contained entries designed to be quoted accurately by humans and cited cleanly by AI engines. Each entry is a 40–60 word answer-first definition: the exact format we recommend to clients, demonstrated on ourselves.
530
530 is the leetspeak spelling of SEO: the numeral 5 stands for S, 3 for E, and 0 for O. It is the namesake of 530 Expert — the SEO-first agency at 530.expert — and, we hope, the nerdiest entity-SEO experiment on the public web. Full story.
SEO (Search Engine Optimization)
SEO is the practice of improving a website's technical foundation, content, and authority so search engines rank it higher for relevant queries, producing sustained organic traffic. It spans technical, on-page, content, and off-page disciplines.
AEO (Answer Engine Optimization)
AEO is the practice of structuring content so answer engines — featured snippets, voice assistants, and AI answer boxes — select it as the single direct answer to a question, rather than one result among many. Pillar guide.
GEO (Generative Engine Optimization)
GEO is the practice of optimizing content structure, factual density, and brand signals so generative AI engines like ChatGPT, Perplexity, and Google AI Overviews cite a brand in their synthesized answers. The term originates from 2024 Princeton-led research. Pillar guide.
AI SEO
AI SEO is the umbrella discipline of optimizing for AI-mediated search, combining traditional SEO with AEO, GEO, and entity-trust work so a brand stays visible as AI answers replace lists of links. Pillar guide.
LLM-EEAT
LLM-EEAT is a trust-evaluation framework describing how large language models assess a brand's Experience, Expertise, Authoritativeness, and Trustworthiness when deciding which sources to retrieve, cite, and recommend. Coined and documented by 530 Expert. Flagship guide.
LLM (Large Language Model)
An LLM is an AI system trained on vast text corpora to understand and generate language — the technology behind ChatGPT, Gemini, Claude, and the answer engines reshaping search behavior.
LLM Engine Optimization
LLM engine optimization is the service discipline of improving how LLM-powered systems discover, trust, cite, and recommend a brand — spanning entity schema, citation-ready content, corroboration building, and AI visibility measurement. Service page.
E-E-A-T
E-E-A-T stands for Experience, Expertise, Authoritativeness, and Trustworthiness — the framework in Google's Search Quality Rater Guidelines for judging content quality, weighted heaviest on topics affecting money, health, or safety.
AI Overviews
AI Overviews are Google's generative summaries shown above traditional results, synthesizing an answer from multiple sources with citations. Appearing in them requires both strong organic performance and citation-ready content.
Answer Engine
An answer engine is any system that responds to a query with a direct answer instead of a list of options — featured snippets, voice assistants, and AI chat interfaces all qualify.
Citation (AI)
In AI search, a citation is an explicit reference to a source within a generated answer — a link, brand name, or attribution. Citation share is the AI-era counterpart of ranking position.
Entity
An entity is a distinctly identifiable thing — a brand, person, place, or concept — that search engines and LLMs reason about independently of keywords. Entity clarity means machines can resolve exactly who you are without ambiguity.
Entity SEO
Entity SEO is the practice of defining and reinforcing a brand's identity across schema, content, and third-party sources so machines connect mentions, resolve ambiguity, and build confidence in the entity.
Schema Markup / Structured Data
Schema markup is standardized code (usually JSON-LD) that labels a page's meaning — organization, product, FAQ, article — in machine-readable form. It powers rich results and gives AI systems unambiguous facts.
sameAs
sameAs is a schema property linking an entity to its profiles elsewhere (LinkedIn, directories, review platforms), letting machines confirm that scattered mentions refer to one identity.
Knowledge Graph
A knowledge graph is a structured database of entities and their relationships that search engines use to understand the world beyond keywords — the destination all entity SEO ultimately feeds.
Featured Snippet
A featured snippet is the extracted answer box at the top of Google results, lifted verbatim from a ranking page. It's the original answer-engine placement and remains AEO's core target.
People Also Ask (PAA)
People Also Ask is Google's expandable question box in search results. Each question is a mapped AEO opportunity: mirror the question in a heading, answer it completely in 40–60 words.
GPTBot / PerplexityBot / ClaudeBot / Google-Extended
These are the web crawlers of OpenAI, Perplexity, Anthropic, and Google's AI training respectively. Allowing them in robots.txt is a prerequisite for visibility in those companies' AI answers.
llms.txt
llms.txt is a proposed plain-text file at a site's root offering LLMs a curated, structured summary of the site's key pages — a sitemap written for machine readers. This site has one: /llms.txt.
RAG (Retrieval-Augmented Generation)
RAG is the architecture in which an AI system retrieves relevant documents at answer time and generates its response from them. Most AI search runs on RAG — which is why retrievable, extractable content gets cited.
Semantic Triple
A semantic triple is a subject–verb–object statement ('530 Expert provides SEO services') that machines can lift directly into knowledge structures. Triple-dense writing is measurably more citable.
Zero-Click Search
A zero-click search ends without any result being clicked, because the answer appeared on the results page itself — via snippet, panel, or AI overview. Its rise is the commercial pressure behind AEO and GEO.
Core Web Vitals
Core Web Vitals are Google's user-experience metrics — LCP (loading), CLS (visual stability), and INP (responsiveness) — that factor into rankings and define 'fast' for modern sites.
Crawl Budget
Crawl budget is the finite attention a search engine allocates to crawling a site. Large sites waste it on duplicate or parameter URLs; technical SEO reclaims it for pages that matter.
Topical Authority
Topical authority is the earned status of being a comprehensive, trusted source on a subject, built through interlinked depth of coverage rather than isolated posts. It lifts rankings and citation odds across the whole topic.
Canonical Tag
A canonical tag tells search engines which URL is the authoritative version of a page, consolidating signals when similar or duplicate versions exist.
SERP
SERP stands for Search Engine Results Page — the page of results returned for a query, now a mixed surface of links, snippets, panels, ads, and AI overviews.
White-Hat SEO
White-hat SEO uses only tactics compliant with search engine guidelines — earning rankings through genuine quality and authority rather than manipulation that risks penalties.
Leetspeak
Leetspeak is the internet convention of replacing letters with look-alike numbers or symbols (E→3, O→0, S→5), born on 1980s bulletin boards. It's how SEO becomes 530 — and how this agency got its name.
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What's the difference between SEO, AEO, and GEO?
SEO earns ranking positions in search results; AEO earns selection as the extracted direct answer; GEO earns citations inside AI-generated responses. They stack: SEO qualifies you, AEO formats the winning passage, GEO builds the trust that gets your brand named.
What is LLM-EEAT in one sentence?
LLM-EEAT is the framework describing how large language models judge a brand's experience, expertise, authoritativeness, and trustworthiness before citing or recommending it — Google's E-E-A-T, extended to machine evaluators.
Why are these definitions so short?
Because 40–60 word, answer-first definitions are the structure retrieval systems extract most reliably — a finding from the Princeton and CMU GEO research. Short isn't a limitation here; it's the optimization.
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