Glossary
Plain-English definitions
The terms you will hear on a project - from headless CMS and Core Web Vitals to hydration and structured data - defined in one clear sentence, then pointed to where each one actually matters.
A
- Answer Engine Optimization (AEO)
- Structuring content so AI answer engines like ChatGPT, Perplexity, Google's AI Overviews and Gemini can understand and cite it. It favours clear, self-contained answers, question-style headings, structured data and genuine expertise over keyword stuffing.
- See alsoDigital marketing and SEO
C
- Core Web Vitals
- Three Google metrics for real-world page experience: Largest Contentful Paint (loading), Interaction to Next Paint (responsiveness) and Cumulative Layout Shift (visual stability). They are measured from real visits and are a Google ranking signal, so they reward a site that loads fast and stays stable.
- See alsoWeb design and developmentWebsite maintenance
- Cumulative Layout Shift (CLS)
- A Core Web Vital that measures how much a page's content unexpectedly moves as it loads, for example when a late image or ad pushes text down. Lower is better; a good CLS is 0.1 or less.
- See alsoWeb design and development
G
- GROQ
- Graph-Relational Object Queries, the open-source query language used to fetch content from Sanity. It reads like a filter over a set of JSON documents: you select the documents you want and shape exactly the fields you need back in a single request.
- See alsoSanity development
H
- Headless CMS
- A content management system that stores and delivers content through an API, with no built-in front end. The website or app that displays the content is built separately and pulls it in, so the same content can feed a site, a mobile app and other channels at once.
- See alsoSanity developmentStrapi developmentContentful developmentDrupal development
- Hydration
- The process where the browser takes server-rendered HTML and attaches JavaScript to it so the page becomes interactive. Until hydration finishes a page can look ready while buttons and inputs do not yet respond, so shipping less JavaScript keeps it fast.
- See alsoReact developmentNext.js development
I
- Incremental Static Regeneration (ISR)
- A Next.js technique that serves static pages but rebuilds them in the background on a schedule or on demand, so content can update without a full site rebuild. It combines the speed of static pages with the freshness of dynamic ones.
- See alsoNext.js development
- Interaction to Next Paint (INP)
- A Core Web Vital that measures how quickly a page responds to a visitor's clicks, taps and key presses across the whole visit. It replaced First Input Delay in 2024; a good INP is 200 milliseconds or less.
- See alsoWeb design and development
L
- Largest Contentful Paint (LCP)
- A Core Web Vital that measures how long the largest element in view (usually the main image or heading) takes to render. It is Google's loading-speed metric; a good LCP is 2.5 seconds or less, measured from real visits.
- See alsoWeb design and development
P
- Portable Text
- An open, JSON-based way to store rich text (headings, links, images, custom blocks) as structured data rather than raw HTML. Because it is structured, the same content can be rendered cleanly on a website, a mobile app or any other front end.
- See alsoSanity development
- Progressive Web App (PWA)
- A website built with web technology that can be installed to a device's home screen and can work offline using features like service workers. It gives an app-like experience without a separate native app or an app-store download.
- See alsoMobile app development
S
- Server-Side Rendering (SSR)
- Generating a page's HTML on the server for each request, then sending it to the browser fully formed. It suits content that changes per user or per request and is strong for SEO because crawlers receive complete HTML, at the cost of some per-request server work.
- See alsoNext.js development
- Single-Page Application (SPA)
- A website that loads one HTML shell and then updates the view with JavaScript as the user navigates, instead of loading a new page each time. It feels app-like after load, but needs care for SEO and first load, which is why public sites often pair it with server rendering.
- See alsoReact development
- Static Site Generation (SSG)
- Building every page into ready-made HTML at build time, before any visitor arrives. The pages are served instantly from a CDN with no per-request work, which makes them fast and cheap to host. Best for content that does not change on every request.
- See alsoNext.js developmentAstro development
- Structured data (JSON-LD)
- Machine-readable labels added to a page, most often as JSON-LD in a script tag, that tell search and answer engines what the content means: an article, a product, an FAQ, an organization. It does not change what users see, but it helps engines understand and cite the page.
- See alsoDigital marketing and SEO
T
- Time to First Byte (TTFB)
- How long the browser waits after requesting a page before it receives the first byte of the response. It reflects server and network speed and sets the floor for every other loading metric; a fast TTFB comes from good hosting, caching and a CDN.
- See alsoWebsite maintenanceNext.js development
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