Glossary
AI Search
Plain-English definitions of AI search terms - from GEO and AEO to LLMs and query fan-out. The landscape is changing fast; here is what actually matters.
AEO (Answer Engine Optimization)
The practice of structuring content so it appears as direct answers in AI-powered search tools like Google AI Overviews, Perplexity, and ChatGPT. AEO focuses on clear, concise, answer-first writing that AI systems can extract and surface easily.
AI Overviews
Google's AI-generated summaries that appear at the top of search results for many queries. AI Overviews pull from multiple sources to synthesise a direct answer. Appearing in an AI Overview can drive significant brand visibility - even without a first-page ranking.
Answer-First Format (BLUF)
A writing structure where the direct answer to a question is placed at the very beginning of a section, before any supporting explanation. BLUF stands for Bottom Line Up Front. This format is favoured by AI systems that extract answers from content, and by users who want quick answers.
ChatGPT
OpenAI's AI assistant, capable of answering questions by drawing on its training data and, increasingly, real-time web browsing. As more users search via ChatGPT rather than Google, optimising content for LLM discoverability is becoming a meaningful part of modern SEO strategy.
Crawlability (for AI)
Whether AI systems can access and process your website's content. Some AI tools respect robots.txt and may be blocked if your site restricts crawling. Making content accessible to AI crawlers is an emerging consideration alongside traditional search engine crawlability.
E-E-A-T
Experience, Expertise, Authoritativeness, and Trustworthiness - the framework Google uses to evaluate content quality. AI systems tend to favour content that demonstrates genuine expertise and real-world experience, making E-E-A-T signals increasingly important for AI search visibility.
GEO (Generative Engine Optimization)
The practice of optimising content to appear in AI-generated search results. GEO extends traditional SEO by focusing on how AI systems select, synthesise, and attribute information - including structured formatting, factual density, and clear sourcing.
Hallucination
When an AI model generates information that is factually incorrect or fabricated, presented with apparent confidence. Hallucinations are a known limitation of LLMs. Well-sourced, clearly structured content on your website can help AI systems cite accurate information about your business.
LLM (Large Language Model)
An AI model trained on vast amounts of text data to understand and generate human-like language. LLMs power tools like ChatGPT, Gemini, and Claude. They are increasingly being used to answer search queries directly, shifting how users discover information online.
Perplexity
An AI-powered search engine that provides direct, cited answers to queries by searching the web in real time. Perplexity is growing in popularity as an alternative to Google, particularly among technical and research-oriented users.
Query Fan-Out
The process AI search engines use to break a complex user query into multiple sub-questions, search for answers to each, and synthesise a comprehensive response. Content that anticipates and answers related sub-questions is more likely to be surfaced across multiple query variations.
RAG (Retrieval-Augmented Generation)
A technique where an AI retrieves relevant information from external sources before generating a response. Google AI Overviews and Perplexity both use RAG - they search the web, retrieve relevant content, then generate a synthesised answer. Well-structured content is more likely to be retrieved and used.
Structured Data
Code added to a page that explicitly describes its content in a format machines can understand. Structured data (typically Schema.org JSON-LD) helps both search engines and AI systems accurately understand who you are, what you do, and what your content covers.
Zero-Click Search
A search result where the user gets their answer directly on the results page - via AI Overviews, featured snippets, or knowledge panels - without clicking through to any website. Zero-click searches are increasing as AI search matures, making brand visibility in these results an important goal even without a click.
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