RESOURCES
The growth glossary.
Last updated: July 2026
26 plain-language definitions spanning AI search & GEO, core SEO, paid media and conversion measurement — the terms behind every channel we run. In short: GEO (Generative Engine Optimization) is the practice of getting cited inside AI-generated answers, and it shares the same fundamentals as classic SEO — the two aren't separate disciplines. The 26 terms below cover AI search & GEO, core SEO, paid media, and conversion & measurement, grouped by theme and alphabetised within each group so you can scan straight to the one you need.
AI search & GEO
- AEO (Answer Engine Optimization)
- The practice of structuring content so answer engines — AI Overviews, ChatGPT, Perplexity, voice assistants — can extract and cite it directly, rather than relying on a click through a results page. By 2026, AEO is increasingly used as another name for GEO rather than a separate discipline — see "GEO" below.
- AI Overview
- Google's AI-generated summary shown above traditional search results, synthesised from multiple sources with citations attached. Appearing in an AI Overview is one of the clearest, measurable forms of AI-search visibility, alongside citations in ChatGPT, Perplexity and Gemini.
- Answer Engine
- Any tool a searcher asks a question of and expects a direct answer from, rather than a list of links to click through. AI Overviews, ChatGPT, Perplexity, Gemini and voice assistants are all answer engines.
- Citation (AI citation)
- An instance of an AI answer engine naming or linking to your brand, page or data as the source behind part of its answer. Citations are the AI-search equivalent of a ranking — and, per current guidance from AI providers, they're earned the same way real search visibility always has been: useful, well-structured, trustworthy content, not shortcuts like an llms.txt file.
- E-E-A-T
- Google's framework for judging content quality: Experience, Expertise, Authoritativeness and Trustworthiness. It isn't a ranking factor you can bolt onto a page directly, but it shapes how both classic search and AI answer engines decide which sources are reliable enough to rank or cite.
- GEO (Generative Engine Optimization)
- The umbrella term for optimising content so it gets surfaced and cited by generative AI systems — AI Overviews, ChatGPT, Perplexity, Gemini and similar. The prevailing guidance is that GEO "is still SEO": the same fundamentals — crawlable pages, clear structure, genuine expertise, structured data — that win classic rankings are what earn AI citations too.
- LLMO (Large Language Model Optimization)
- A narrower term, sometimes used interchangeably with GEO, for shaping how large language models describe, summarise or recommend a brand — including in contexts with no live search step, such as a model drawing on what it learned during training.
- Schema markup (structured data)
- Standardised code — usually JSON-LD — added to a page that explicitly labels what its content means: a product, a review, a FAQ, an organisation. Well-implemented schema is one of the most reliable levers for both rich search results and AI-answer citations.
- Share of voice
- The proportion of visibility your brand captures in a given space relative to competitors — measured in classic search rankings, or, increasingly, the proportion of AI-generated answers on your topics that cite or mention your brand, tracked with tools like Profound and Otterly.ai.
Search & SEO fundamentals
- Backlink
- A link from another website to yours. Backlinks from relevant, trustworthy sites remain one of the strongest signals of authority for both classic search rankings and AI-answer citations.
- Core Web Vitals
- Google's three real-world speed and stability metrics — Largest Contentful Paint (loading speed), Interaction to Next Paint (responsiveness) and Cumulative Layout Shift (visual stability) — used as a ranking signal and a genuine measure of user experience.
- Crawl budget
- The number of pages a search engine's crawler will visit on your site within a given period. It mostly matters for very large sites; a clean site architecture with few wasted crawl paths keeps important pages found and refreshed.
- Domain authority
- A third-party (not Google-published) metric — most commonly Moz's — that scores a domain's likely ranking strength from accumulated backlinks and trust signals, on a 1–100 scale. Useful for benchmarking against competitors, but not an official Google ranking factor.
- Hreflang
- An HTML attribute that tells search engines which language and regional version of a page to show a given searcher, so a UK visitor and a German visitor land on the right localised version of the same content.
- Local SEO
- Optimising for location-based search — Google Business Profile, local citations, maps rankings and reviews — so a business shows up for "near me" and location-qualified searches.
- SEO (Search Engine Optimization)
- The practice of improving a website's visibility in organic (unpaid) search results, spanning technical foundations, on-page content, off-page authority (backlinks) and, increasingly, how that same content performs in AI-search citations.
- SERP (Search Engine Results Page)
- The page a search engine shows after a query — a mix of organic results, ads, AI Overviews, maps packs and other features, all competing for the same attention.
Paid media
- CPA (Cost Per Acquisition)
- The average amount spent on advertising to generate one conversion — a sale, lead or sign-up. The metric that ultimately decides whether a paid campaign is profitable.
- CPC (Cost Per Click)
- The amount an advertiser pays each time someone clicks a paid ad. A useful efficiency metric, but only meaningful alongside conversion rate and CPA — a cheap click that never converts isn't a bargain.
- CTR (Click-Through Rate)
- The percentage of people who see an ad or search result and click it, calculated as clicks divided by impressions. A strong signal of how compelling a headline or ad is — though a high CTR alone doesn't guarantee a sale.
- PPC (Pay-Per-Click)
- Paid advertising — on Google, Meta, LinkedIn or elsewhere — where an advertiser pays each time their ad is clicked, as opposed to a flat fee for impressions shown.
- ROAS (Return on Ad Spend)
- Revenue generated for every pound spent on advertising, expressed as a ratio — a ROAS of 5x means £5 of revenue for every £1 spent. The headline metric for judging whether paid media is actually paying back.
Conversion & measurement
- A/B testing
- Showing two versions of a page, email or ad to different visitors and measuring which performs better against a defined goal, before rolling the winner out to everyone. Reliable A/B testing runs until a result reaches statistical confidence, not until it 'looks' like a winner.
- Attribution modelling
- The method used to decide which marketing touchpoints get credit for a conversion. Simple models, like 'last click,' credit only the final touchpoint; multi-touch attribution spreads credit across every channel that influenced the sale, giving a fairer view of what's actually working.
- CRO (Conversion Rate Optimization)
- The practice of improving the percentage of visitors who complete a desired action — buying, enquiring, signing up — through structured testing and analysis, rather than guesswork or redesigning on instinct.
- Marketing automation
- Software that triggers marketing actions — an email, a retargeting ad, a lead-score update — automatically based on a person's behaviour, such as an abandoned cart or a form submission, rather than a manually sent broadcast.