How to read this article
Every term below has a one-paragraph definition in plain English. The full glossary lives at /glossary with cross-links between related terms. This article picks the 60 terms that matter most when you're evaluating a web design quote, reviewing a proposal, or trying to understand why your existing site isn't performing.
For each term: what it means, why it matters, and (for the technical ones) what to ask if a vendor uses it.
Design terms
Above the fold. The portion of a webpage visible without scrolling. The most-seen real estate on every site.
Hero section. The large block at the top of a page — typically a headline, supporting copy, and a primary call-to-action. The hero often determines whether visitors keep scrolling or bounce.
Call-to-action (CTA). A specific instruction asking the user to do something. "Start a project," "Get a quote," "Sign up." Effective CTAs are visually distinct and action-oriented.
Wireframe. A low-fidelity structural sketch of a page — boxes and labels, no color or typography. Wireframes settle structure before visual design.
Mockup. A high-fidelity static image of a page in Figma showing final colors, typography, imagery. Static — no interaction.
Prototype. An interactive simulation of a page or feature. Used to test interactions before development.
Responsive design. A site whose layout adapts fluidly to any screen size. The opposite is a fixed-width site that looks broken on mobile.
Mobile-first. Designing the smallest screen first and scaling up. Tends to produce simpler, faster designs.
Design system. A documented library of reusable components and styles. Critical for sites with more than 10 pages — without one, the visual treatment fragments fast.
UX vs UI. UX is the complete experience (flow, friction, emotion). UI is the visual surface (buttons, type, color). A site can have great UI and bad UX, or vice versa.
Development terms
HTML, CSS, JavaScript. The three foundational languages of the web. HTML is structure, CSS is style, JavaScript is interaction. Every site uses all three; the differences come in how much of each.
TypeScript. A typed version of JavaScript. Catches a class of bugs that plain JavaScript doesn't. Standard in modern professional development.
React. A JavaScript library for building user interfaces using a component model. The dominant front-end library in 2026.
Next.js. A React framework adding server-side rendering, routing, and deployment. The default for production React sites that need SEO.
SSR (Server-Side Rendering). Rendering pages on the server before sending HTML to the browser. Critical for SEO — crawlers see fully-rendered content immediately.
SSG (Static Site Generation). Pre-rendering pages at build time and serving them as static files. The fastest possible delivery method.
SPA (Single-Page Application). A site that loads once and dynamically updates content without full reloads. Faster feel, but historically harder for SEO.
Headless CMS. A content management system that exposes content via API without dictating the front-end. Lets editors update content while developers build whatever front-end they want.
WordPress. A traditional CMS that bundles editing and rendering. Powers about 40% of the web. Tends toward bloat and ongoing maintenance burden.
Tailwind CSS. A utility-first CSS framework. Dominant in modern web development. Some agencies (us included) prefer vanilla CSS for tighter control.
SEO terms
SEO. Search engine optimization. Everything that affects whether your site shows up in Google. Splits into technical, on-page, and off-page work.
LLM SEO. Optimizing for citation by AI assistants — ChatGPT, Claude, Perplexity, Gemini. New surface in 2024–26. Overlaps heavily with traditional SEO.
llms.txt. A proposed convention (llmstxt.org) for sites to expose a curated Markdown summary at /llms.txt for LLM ingestion.
Structured data / JSON-LD. Machine-readable metadata in a webpage describing what the page is about. Powers rich results in Google and is critical for LLM citation.
Schema.org. The shared vocabulary used in JSON-LD. Defines types like Organization, Article, FAQPage, Service.
Canonical URL. The preferred URL when multiple URLs serve the same content. Tells Google which version to index.
Meta description. A 150-160 character summary describing a page, shown under the title in search results. Influences click-through rate.
Title tag. The HTML <title> element. Becomes the headline in Google search results.
robots.txt. A file at the root of a site telling crawlers which paths are off-limits.
sitemap.xml. A file listing all URLs on a site that should be indexed. Submit to Google Search Console.
Crawler / Bot. Automated software that traverses the web. Googlebot, Bingbot, GPTBot, ClaudeBot.
Indexing. The process by which Google stores a crawled page in its searchable database. Crawled doesn't always mean indexed.
Backlink. A link from another site to yours. One of Google's primary ranking signals.
Domain authority. A general measure of a site's ranking strength, scored 0-100 by various tools.
Alt text. Descriptive text on an <img> tag. Serves accessibility and image SEO.
Performance terms
Core Web Vitals. Google's three ranking-relevant performance metrics: LCP, INP, CLS.
LCP (Largest Contentful Paint). Time for the largest above-the-fold element to render. "Good" is under 2.5s on mobile.
INP (Interaction to Next Paint). Time between user interaction and visual response. "Good" is under 200ms.
CLS (Cumulative Layout Shift). A measure of unexpected content shifting during load. "Good" is under 0.1.
Lighthouse. Google's free auditing tool. Built into Chrome DevTools.
Lazy loading. Loading resources only when needed. Reduces initial page weight.
CDN. Content Delivery Network — geographically distributed servers that cache and serve content close to users. Reduces latency.
WebP, AVIF. Modern image formats with significantly better compression than JPEG/PNG.
Motion terms
GSAP. GreenSock Animation Platform — the industry-standard timeline animation library.
ScrollTrigger. A GSAP plugin for scroll-driven animations.
Three.js. A JavaScript library for 3D graphics in the browser, built on WebGL.
WebGL. Browser API for hardware-accelerated 2D/3D graphics.
Shader. A GPU program that determines pixel colors or vertex positions. Powers custom visual effects.
Lenis. A smooth-scroll library that replaces native scrolling with eased motion.
prefers-reduced-motion. A CSS media query detecting whether the user has opted out of animation in their OS settings. Respecting it is non-negotiable.
Brand terms
Brand identity. The visual + verbal system defining how a brand looks and sounds. Logo, typography, color, voice.
Logo. A graphic mark identifying a brand. Includes wordmarks, monograms, symbol marks, combinations.
Wordmark. A logo composed entirely of typography.
Style guide. Document codifying a brand's visual rules.
E-commerce terms
Conversion rate. The percentage of visitors who complete a defined action. The most-watched metric on commercial sites.
Checkout. The flow from cart to completed purchase. Optimization here directly affects revenue.
Shopify. Leading e-commerce platform. Custom Shopify themes outperform off-the-shelf themes on Core Web Vitals.
Accessibility terms
Accessibility (a11y). Building sites usable by people with disabilities. Often legally required.
WCAG. Web Content Accessibility Guidelines. The international standard for web accessibility.
The full glossary, with cross-links between related terms, lives at /glossary.