Introduction An introduction to Semantic UI open book Guide
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Introduction

What is Semantic UI?

Semantic UI is three things:

  1. A component library: buttons, dropdowns, modals, menus all ready to use
  2. An authoring framework: for building your own components with reactive state and templating
  3. A theming system: CSS tokens for color, spacing, and light/dark mode that govern all components

Components are native Web Components. They work in React, Vue, Svelte, or plain HTML—no adapters, no framework-specific versions.

Semantic ships with signals-based reactivity, AST-compiled templates, and runs natively in the browser without a build step. Learn more →

Using Components

Pick from primitives, components, and behaviors. Use them as HTML tags. Theme with CSS variables.

Building Components

Create custom components like <order-form> or <user-profile> using the same tools the library is built with. Your components inherit the theming system automatically.

Get Started

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Why Semantic?