The complete glossary of AI search, GEO, AEO and SEO in 2026
50+ terms defined for the new era of generative search. Updated May 2026 to reflect ChatGPT-5 with browse, Google AI Overviews global rollout, Perplexity’s Comet browser launch, and the consolidation of GEO/AEO as standalone disciplines distinct from classical SEO.
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Core concepts
SEO (Search Engine Optimization)
The discipline of optimizing web pages to rank highly in classical search engine results pages (SERPs). Born in the late 1990s. Primary engine: Google. Primary signals: backlinks, on-page content, technical performance, intent match. Still relevant in 2026 but no longer sufficient.
GEO (Generative Engine Optimization)
The discipline of optimizing content to be cited and recommended inside AI-generated answers. Engines: ChatGPT, Perplexity, Google Gemini, Anthropic Claude, Microsoft Copilot. Primary signals: structured data, entity clarity, factual density, third-party authority, recency.
AEO (Answer Engine Optimization)
Often used interchangeably with GEO. Some practitioners distinguish: AEO = optimizing for direct answer features (Featured Snippets, AI Overviews); GEO = broader optimization for any generative output. We treat them as overlapping with shared methods.
LLM (Large Language Model)
Neural networks trained on massive text corpora that generate human-like text. Examples: GPT-5 (OpenAI), Claude 3.5 (Anthropic), Gemini 2 (Google), Llama 3 (Meta). LLMs power all major AI search engines in 2026.
RAG (Retrieval-Augmented Generation)
The technique most modern AI engines use to ground responses: instead of relying purely on training data, the model first retrieves relevant documents from the live web (or a knowledge base), then synthesizes an answer citing those sources. Why your fresh, well-structured pages can be cited.
AI Overview (AIO)
Google’s AI-generated answer that appears at the top of search results pages for many queries since 2024. Synthesizes information from multiple web sources. Cites typically 3-4 URLs. Replaces the need to click through to traditional results for ~30% of informational queries.
Featured Snippet
A direct extract from a single web page that Google displays at position zero of the SERP. Predates AI Overviews. Different mechanism: extracts an existing passage rather than synthesizing new text. Still active in 2026 alongside AI Overviews.
AI engines and platforms
ChatGPT
OpenAI’s conversational AI, 800M weekly active users in March 2026. Most-cited generative engine for brand discovery in 2026. With browse mode (default since GPT-5), actively cites web sources.
Perplexity
AI search engine specialized in citing sources. Highest source density per response (mean 6.2 sources). 56M weekly users. Strong recency bias (favors content updated in last 90 days).
Google Gemini
Google’s LLM, integrated across Search (AI Overviews), Workspace, Android. Mixes training data with grounded sources. Conservative citer compared to Perplexity.
Claude
Anthropic’s LLM, used both as consumer chatbot and via API by businesses. Most conservative citer (mean 2.1 sources). When Claude cites you, it considers you a primary source.
Microsoft Copilot
Microsoft’s AI assistant, powered by GPT-4o + Bing search. Integrated in Windows, Office, Edge. Primarily B2B/productivity audience.
Apple Intelligence
Apple’s on-device AI layer (iOS 18+, macOS 15+). Mostly local processing, with optional ChatGPT and Gemini fallback. Expected to grow as a discovery channel through 2027.
Optimization signals
Schema.org
The vocabulary used to add structured data to web pages, helping crawlers understand content. Critical for GEO. Top-priority schemas in 2026: Organization, LocalBusiness, Hotel, Restaurant, Product, FAQPage, HowTo, Article, BreadcrumbList.
FAQ Schema
Specific schema (FAQPage) marking up question-answer pairs. Adds +90% citation lift on average across CapstonAI customer pages. The cheapest, fastest schema win in 2026.
JSON-LD
The recommended format for embedding Schema.org data in HTML pages. Sits in a `
