SEO · AEO · GEO · LLMO · Entity Optimization
A reference for marketers, content strategists, and technical practitioners working across the full discovery ecosystem — traditional search engines, AI assistants, generative answer engines, and everything in between.
How to use this glossary
The lines between SEO, AEO, GEO, and LLMO blur in practice. A single piece of content can be crawled by Googlebot, retrieved by Perplexity, cited by ChatGPT, and summarized in Google’s AI Mode — all from the same URL. Terms are grouped by their primary domain, but most concepts cross over. Where a term has a common abbreviation, it is shown in parentheses.
Download a free visual version of the glossary here: SEO, AI, and LLM optimization guide
1. Foundational Search Concepts
| Term | Definition |
|---|---|
| Search Engine Optimization (SEO) | The discipline of improving a website’s visibility in search engines (Google, Bing, etc.) to earn unpaid, organic traffic. |
| Search Engine Results Page (SERP) | The page returned after a search query, now often a mix of links, AI summaries, ads, maps, videos, and rich features. |
| Organic Traffic | Visitors who arrive from unpaid search listings, as opposed to paid ads, social, email, or direct visits. |
| Ranking Factor | Any signal a search engine or AI system uses to decide the order or eligibility of results. |
| Keyword | A word or phrase users type or speak when searching. Still useful, but increasingly secondary to intent and entities. |
| Search Intent | The underlying goal of a query, typically classified as informational, navigational, transactional, or commercial investigation. |
| Query | The exact phrase entered into a search engine or AI assistant. |
| Long-Tail Query | A longer, more specific query (often 4+ words). Long-tail queries dominate AI assistant usage because users speak more naturally. |
| Zero-Click Search | A search where the user’s need is satisfied directly on the results page (snippet, AI Overview, map pack) without clicking any website. |
| Click-Through Rate (CTR) | Percentage of users who click a given result after seeing it. |
| Bounce Rate | The share of sessions that end without further interaction. Less emphasized today than engagement metrics. |
| Dwell Time | How long a user remains on a page before returning to the SERP. A rough proxy for content satisfaction. |
| Search Satisfaction | Whether the user’s underlying need was met. The end goal that most modern ranking signals try to approximate. |
2. Crawling, Indexing & Infrastructure
| Term | Definition |
|---|---|
| Crawl | The process of a bot fetching pages from the web. |
| Indexing | Storing and organizing crawled pages so they can be retrieved in response to queries. |
| Deindexing | Removal of a URL from a search engine’s index, intentionally or otherwise. |
| Crawl Budget | The number of URLs a search engine is willing to crawl on a site within a given period. Matters mainly for very large sites. |
| Bot / Crawler | Automated software that fetches web pages. Includes traditional search crawlers and AI/LLM crawlers. |
| Googlebot | Google’s primary web crawler. |
| Bingbot | Microsoft Bing’s crawler, which also feeds ChatGPT Search and Copilot. |
| GPTBot | OpenAI’s crawler used for training and retrieval. |
| ClaudeBot | Anthropic’s crawler. |
| PerplexityBot | Perplexity’s crawler. |
| Google-Extended | A user-agent token Google uses to let publishers opt out of Gemini and Vertex AI training without affecting search rankings. |
| Sitemap | An XML file listing a site’s important URLs to help crawlers discover content. |
| Robots.txt | A plain-text file at the root of a site that tells crawlers which paths they may or may not access. Honor depends on the bot. |
| llms.txt | A proposed plain-text file at the root of a site that gives LLMs a curated, structured map of the site’s most important content for retrieval and citation. |
| Canonical URL | The preferred version of a page when duplicates or near-duplicates exist. |
| HTTP Status Codes | Server responses such as 200 (OK), 301 (permanent redirect), 302 (temporary), 404 (not found), 410 (gone), 500 (server error). |
| 301 Redirect | A permanent redirect that passes ranking signals to the destination URL. |
| 404 Error | A response indicating the requested page does not exist. |
| Soft 404 | A page that returns a 200 status but offers no real content, often misclassified by Google. |
| JavaScript SEO | The practice of ensuring JS-rendered content can be crawled, rendered, and indexed correctly. |
| Rendering | The step where a crawler executes a page’s JavaScript to see the final DOM. |
| Server Response Time | How quickly a server begins returning a page; a component of Core Web Vitals. |
| Render-Blocking Resources | CSS or JS that delays the browser from showing visible content. |
| Lazy Loading | Deferring the load of images, videos, or scripts until they are needed. |
| CDN (Content Delivery Network) | A geographically distributed network that caches and serves assets closer to users. |
| Edge SEO | Applying SEO changes (redirects, headers, A/B tests, schema injection) at the CDN edge rather than in the origin application. |
| Headless CMS | A content management system that exposes content via API, with the front end built separately. |
| API | An interface that lets systems exchange data programmatically. |
| Log File Analysis | Reviewing server logs to study how bots crawl a site — what they hit, what they miss, what they waste. |
| SSL / TLS Certificate | Encryption that enables HTTPS. A baseline trust and ranking signal. |
| Core Web Vitals | Google’s set of user-experience metrics: LCP (loading), INP (interactivity, replaced FID in 2024), and CLS (visual stability). |
| Mobile-First Indexing | Google’s standard practice of using the mobile version of a page as the primary basis for indexing and ranking. |
| Page Experience | A composite signal covering Core Web Vitals, HTTPS, and absence of intrusive interstitials. |
3. On-Page, Content & Semantic Optimization
| Term | Definition |
|---|---|
| On-Page SEO | Optimization applied directly to a page: content, headings, internal links, metadata, schema. |
| Off-Page SEO | External factors influencing rankings: backlinks, brand mentions, citations, reputation. |
| Technical SEO | Optimization of the underlying infrastructure: crawlability, indexing, performance, rendering, architecture. |
| Meta Title (Title Tag) | The HTML <title> element, used as the clickable headline in most SERP listings. |
| Meta Description | A short summary in the page’s <meta> tag, often shown beneath the title in results. |
| Heading Tags | HTML elements <h1> through <h6> that signal content structure to both users and machines. |
| Alt Text | The alt attribute describing an image — important for accessibility and for AI/image understanding. |
| URL Slug | The human-readable portion of a URL identifying the page. |
| Internal Linking | Links between pages on the same domain, used to distribute authority and signal topical relationships. |
| Pillar Content | A comprehensive, central piece of content covering a broad topic in depth. |
| Topic Cluster | A pillar page plus interlinked supporting pages, designed to demonstrate topical depth and authority. |
| Evergreen Content | Content that remains relevant and accurate over long periods. |
| Thin Content | Pages with little original or useful information — a known risk for demotion. |
| Duplicate Content | Substantially similar content on multiple URLs, on the same site or across sites. |
| Content Freshness | How recently a page has been meaningfully updated. Important for time-sensitive topics. |
| Content Decay | The gradual decline in traffic and rankings as content ages or competitors improve. |
| Helpful Content | Google’s framing (since the 2022 Helpful Content Update) for content created primarily for people, not search engines. |
| Readability | How easily a human reader can understand a piece of content. Often measured with formulas like Flesch-Kincaid. |
| NLP Optimization | Structuring writing — clear subjects, plain syntax, defined entities — so natural language processing systems can parse and reuse it. |
| Semantic Search | Search that interprets meaning and context rather than matching exact keywords. |
| Semantic Relevance | How closely a piece of content aligns with the meaning and intent behind a query, not just its words. |
| LSI Keywords | “Latent Semantic Indexing” terms — a popular but largely debunked SEO concept. Google has stated it does not use LSI. The useful underlying idea is “topically related terms.” |
4. Authority, Trust & E-E-A-T
| Term | Definition |
|---|---|
| Backlink | An inbound link from another website pointing to yours. Still a core authority signal. |
| Anchor Text | The clickable text of a hyperlink, which gives search engines context about the destination. |
| Domain Authority (DA) | A third-party score (originally from Moz) estimating a domain’s ranking strength. Not used by Google itself. |
| Domain Rating (DR) | Ahrefs’ equivalent metric, based on backlink profile. |
| Topical Authority | The degree to which a site is recognized as expert across a defined subject area. |
| E-E-A-T | Google’s quality framework: Experience, Expertise, Authoritativeness, and Trustworthiness. The first “E” (Experience) was added in 2022. |
| YMYL (“Your Money or Your Life”) | Google’s classification for topics that can materially affect health, finances, safety, or wellbeing — held to a higher E-E-A-T standard. |
| Brand Mention | An unlinked reference to a brand. Increasingly important as an authority and entity signal for both search and LLMs. |
| Citation (Local) | An online listing of a business’s name, address, and phone number. |
| NAP Consistency | Keeping Name, Address, and Phone identical across directories and platforms. |
| Reputation Signals | Reviews, ratings, press coverage, and discussion across the web that shape both human and AI perception. |
5. Structured Data & Entities
| Term | Definition |
|---|---|
| Structured Data | Machine-readable code that explicitly labels what a page is about. |
| Schema Markup | The structured data vocabulary maintained at Schema.org, typically implemented as JSON-LD. |
| JSON-LD | The recommended format for adding schema, embedded in a <script> tag. |
| Rich Results | Enhanced SERP listings — stars, FAQs, product info, recipe cards — driven by structured data. |
| Featured Snippet | A highlighted answer box at the top of Google’s results, extracted from a ranking page. |
| Position Zero | Common name for the featured snippet position, above the standard “blue links.” |
| Knowledge Graph | Google’s database of entities (people, places, things, concepts) and the relationships between them. |
| Knowledge Panel | The branded info box appearing on the right side of Google results, drawn from the Knowledge Graph. |
| Entity | A distinct, identifiable concept — a person, organization, place, product, or idea — that search engines and LLMs can recognize. |
| Entity SEO | Optimizing for clearly defined entities and their relationships, not just keyword strings. |
| Brand Entity | The cluster of signals — name, descriptions, mentions, schema, Wikipedia/Wikidata presence — that establishes a brand as a recognized entity to machines. |
| Entity-Based Optimization | Building content and signals around concepts and their connections, often validated via knowledge graphs. |
| Wikidata / Wikipedia Presence | Strong external signals used by both Google and LLMs to verify and disambiguate entities. |
| Speakable Schema | A schema.org property designed to flag content suitable for voice assistant readout. |
| FAQ Schema | Structured data marking up question/answer pairs (note: Google has reduced FAQ rich result eligibility since 2023). |
6. Local & Multi-Channel Search
| Term | Definition |
|---|---|
| Local SEO | Optimization for geographically targeted queries and map-based results. |
| Google Business Profile (GBP) | Google’s business listing platform (formerly Google My Business), powering Maps and local pack results. |
| Map Pack / Local Pack | The block of local business results shown with a map in Google search. |
| Local Citation | A mention of a business’s NAP information on a third-party site. |
| Search Everywhere Optimization | The practice of optimizing for visibility across every place users discover information — Google, Bing, YouTube, TikTok, Reddit, Amazon, Apple/Google Maps, and AI assistants. |
| Omni-Search Visibility | A brand’s combined presence across all of these discovery surfaces. |
| Platform SEO | Optimization tailored to a specific platform’s algorithm — YouTube, TikTok, Amazon, Pinterest, App Store, etc. |
| Forum / Community Optimization | Building presence and helpful contributions on Reddit, Quora, Stack Exchange, and niche communities — increasingly important because LLMs heavily cite these sources. |
7. AI Search, LLMs & Generative Optimization
This section covers the overlapping disciplines often labeled AEO (Answer Engine Optimization), GEO (Generative Engine Optimization), and LLMO (LLM Optimization). The boundaries between them are fuzzy; in practice they describe the same goal — being surfaced and cited by AI-mediated discovery — from slightly different angles.
7a. Core AI search vocabulary
| Term | Definition |
|---|---|
| Large Language Model (LLM) | A neural network trained on massive amounts of text to understand and generate language. Examples: OpenAI’s GPT, Anthropic’s Claude, Google’s Gemini, Meta’s Llama. |
| Generative AI | AI systems that produce new content (text, images, audio, video) rather than only classifying or retrieving. |
| AI Search | A search experience powered primarily by generative AI, which synthesizes an answer from multiple sources rather than listing links. |
| AI Assistant | A conversational AI product such as ChatGPT, Claude, Gemini, Copilot, or Perplexity. |
| Answer Engine | A system designed to deliver direct answers (Perplexity, ChatGPT Search, Google AI Mode) rather than ten blue links. |
| AI SERP | A search results page enhanced or replaced by AI-generated content. |
| AI Overview | Google’s AI-generated summary block that appears above traditional results for many queries (the successor to “Search Generative Experience” / SGE). |
| AI Mode (Google) | Google’s dedicated generative search experience offering full conversational answers, launched broadly in 2025. |
| ChatGPT Search | OpenAI’s search feature inside ChatGPT, which retrieves and cites live web sources. |
| Perplexity | A standalone answer engine that combines retrieval, citation, and conversation. |
| Copilot (Microsoft) | Microsoft’s AI assistant, integrated with Bing search results. |
| AI Snapshot | A generic term for any AI-generated summary appearing in a search interface. |
| Conversational Search | Search expressed in natural, often multi-turn dialogue rather than terse keywords. |
| Multimodal Search | Search combining text, images, voice, and/or video inputs and outputs. |
| Voice Search | Search performed by speaking, typically through a phone, smart speaker, or in-car assistant. |
| Agentic Search | Search performed by an autonomous AI agent that can browse, compare, and take actions (book, buy, summarize) on the user’s behalf. |
7b. How AI systems find and use content
| Term | Definition |
|---|---|
| Retrieval-Augmented Generation (RAG) | An architecture where an LLM retrieves relevant external documents at query time and uses them to generate a grounded answer. |
| AI Retrieval | The lookup step in which an AI system gathers supporting documents before generating an answer. |
| Vector Search | Retrieval based on semantic similarity in an embedding space, rather than exact keyword matching. |
| Embedding | A numerical vector that represents the meaning of text, an image, or another input — the unit of comparison in vector search. |
| Chunking | Splitting long documents into smaller, semantically coherent segments so they can be embedded and retrieved efficiently. |
| Grounding | Anchoring an AI’s response in verified, retrievable source material to reduce hallucination. |
| AI Hallucination | Confidently stated but incorrect or fabricated AI output. |
| Source Attribution | The AI system identifying which sources it used to construct an answer. |
| AI Citation | A specific in-response reference (link, footnote, badge) pointing to a source. |
| AI Mention | Any reference to a brand, product, or person inside an AI-generated response, with or without a link. |
| Knowledge Retrieval | The general process of an AI system locating and extracting information from indexed sources. |
| Context Window | The maximum amount of text an LLM can consider in a single request — relevant to how much content a system can ingest before answering. |
| Prompt | The input given to an AI model. |
| Prompt Engineering | The craft of writing prompts to reliably produce useful outputs. |
| Prompt Injection | An attack in which hidden instructions in a webpage or document attempt to manipulate an LLM’s behavior. A real risk for AI-readable content. |
| AI Training Data | The corpus used to train a model. Distinct from retrieval data, which is fetched at query time. |
| Fine-Tuning | Additional training applied to a base model to specialize its behavior or knowledge. |
7c. Optimizing for AI visibility
| Term | Definition |
|---|---|
| Answer Engine Optimization (AEO) | Structuring content so that answer engines and AI assistants can extract a direct, accurate response. Heavy on clear question-answer formatting, schema, and concise lead-ins. |
| Generative Engine Optimization (GEO) | The broader practice of optimizing content to be retrieved, synthesized, and cited by generative AI search systems. |
| LLM Optimization (LLMO) | Optimizing so that LLMs — both at training time and at retrieval time — can understand, attribute, and reproduce information about a brand or topic. |
| AI Visibility | How often, and how favorably, a brand or source appears inside AI-generated answers. The AI-era equivalent of share-of-voice. |
| AI Discoverability | How easily an AI system can find a brand or piece of content when it would be relevant. |
| AI Crawlability | Whether AI bots can technically access a site (robots.txt, authentication, rendering). |
| AI Indexability | Whether a site’s content can be parsed, chunked, and stored by AI systems for later retrieval. |
| Machine Readability | How cleanly a system can interpret a page — clear HTML, semantic markup, plain language, accessible structure. |
| AI-Friendly Content | Content explicitly structured for machine consumption: clear claims, direct answers, defined entities, attributable statements. |
| Citation Optimization | Writing and structuring content to maximize the chance of being cited by AI systems (concrete facts, unique data, clear attribution, stable URLs). |
| Citation Graph | The network of who cites whom across the web — increasingly used by AI systems to weight authority. |
| Citation Authority | The likelihood that a given source will be referenced by AI systems on a given topic. |
| Contextual Authority | Authority that comes from covering the entire ecosystem of a topic, not just a single page. |
| AI Trust Signals | Signals — author bios, citations, schema, consistent brand entity, third-party validation — that lead AI systems to treat a source as reliable. |
| Retrieval Signals | Whatever cues a retrieval system uses to select content: freshness, relevance, authority, structure, embeddings quality. |
| AI Ranking Signals | The factors that determine whether and how prominently an AI system features a source. |
| Source Authority | The perceived overall trustworthiness of a source as judged by an AI system. |
| Question Optimization | Writing content around the actual questions users ask, often in their own phrasing. |
| Conversational Content | Content that reads as if it directly answers a question, in the register of a knowledgeable conversation. |
| FAQ Optimization | Structuring FAQs (both on-page and in schema) for snippet and AI retrieval. |
| Knowledge Entity | A clearly defined entity that AI systems can recognize and reason about. |
| Trust Layer Optimization | Building credibility signals — reviews, mentions, authorship, third-party validation — across the wider web, not just on-site. |
| Machine-First SEO | Designing for machine consumption and human consumption simultaneously, rather than treating them as competing goals. |
| Parasite SEO / AI Parasite Marketing | The practice of ranking or being cited via high-authority third-party platforms (Reddit, LinkedIn, YouTube, major publications) rather than your own domain. |
| Digital Entity Footprint | The total picture of a brand across the web — owned, earned, and third-party — that defines it as an entity. |
| AI Search Ecosystem | The combined environment of traditional engines, AI assistants, and answer engines that now shapes discovery. |
| Human + AI Search Journey | The reality that a single buying or research journey now spans Google, ChatGPT, Reddit, YouTube, and others before a decision is made. |
8. Analytics & Measurement
| Term | Definition |
|---|---|
| Impressions | The number of times a piece of content has appeared in a results interface. |
| Sessions | Visits to a website, as tracked in analytics. |
| Users | Unique visitors over a given period. |
| Engagement Rate | The share of sessions considered meaningful (by duration, depth, or conversion). The metric that largely replaced bounce rate in GA4. |
| Conversion Rate | The percentage of visitors who complete a defined goal. |
| Organic Conversions | Conversions attributable to unpaid search traffic. |
| Attribution | The methodology used to assign credit for a conversion across the channels that touched it. |
| Key Performance Indicator (KPI) | A specific, measurable metric tied to business outcomes. |
| Google Search Console (GSC) | Google’s free tool for monitoring crawl, index, and search performance. |
| Bing Webmaster Tools | Microsoft’s equivalent, also useful for understanding how content surfaces in Bing, Copilot, and ChatGPT Search. |
| Crawl Errors | Issues — server, redirect, blocking, or not-found — that prevent crawlers from accessing content. |
| Index Coverage | A report in Search Console showing which pages are indexed, excluded, or in error. |
| Share of AI Voice | An emerging metric estimating how often a brand is named in AI-generated responses to relevant prompts. |
| AI Citation Tracking | Monitoring which AI systems cite a brand or page, for which queries, with what framing. |
Quick reference: the four “O”s
| Acronym | Stands for | Primary focus |
|---|---|---|
| SEO | Search Engine Optimization | Ranking in traditional search results (Google, Bing). |
| AEO | Answer Engine Optimization | Being chosen as the direct answer in snippets and AI assistants. |
| GEO | Generative Engine Optimization | Being retrieved, synthesized, and cited inside AI-generated answers. |
| LLMO | LLM Optimization | Being understood and reproduced correctly by large language models, both via training data and live retrieval. |
In practice, the same well-structured, authoritative, machine-readable content tends to win across all four. The acronyms describe emphasis, not separate disciplines.
Last updated: 2026.
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