---
title: "React"
description: "React is a JavaScript library for building user interfaces from components and a virtual DOM. Learn about JSX, hooks and its use in modern web applications."
url: "https://nodea.io/en/glossary/react"
lang: "en"
updated: "2026-07-13"
---

# React

> React is a popular JavaScript library for building user interfaces from reusable components using a virtual DOM mechanism.

**React** is an open-source [JavaScript](https://nodea.io/en/glossary/javascript) library for building user interfaces, created and maintained by Meta (Facebook). It is built on the idea of reusable components and a declarative description of the interface, where the developer states what the view should look like for a given data state and React handles updating the screen efficiently. It is one of the most popular front-end technologies in the world.

## How React works

React rests on several key mechanisms:

- **Components** — the interface is split into independent, nestable blocks (buttons, forms, lists) that can be reused in many places.
- **JSX** — a syntax that blends JavaScript with an HTML-like notation, letting you describe the view structure directly in a component's code.
- **Virtual DOM** — React keeps a lightweight copy of the [DOM](https://nodea.io/en/glossary/virtual-dom) tree in memory, compares it after each state change and updates only the parts of the page that actually changed.
- **Hooks** — functions like *useState* and *useEffect* let you manage state and side effects in function components.

Thanks to a one-way data flow, React apps are predictable and easier to debug.

## React in practice

React shines when building modern, interactive interfaces:

1. **Single-page applications** — it is a natural choice for building a [SPA](https://nodea.io/en/glossary/single-page-application), where content changes without a full page reload.
2. **Server-side rendering** — frameworks built on React (e.g. Next.js) add SSR, routing and performance optimizations.
3. **Mobile apps** — React Native lets you build native iOS and Android apps using the same component logic.

In the front-end ecosystem, React competes with [Vue.js](https://nodea.io/en/glossary/vue-js) and [Angular](https://nodea.io/en/glossary/angular); the technology choice depends on project scale, team skills and performance requirements.

### Is React a framework or a library?

Technically, React is a library focused on the view (UI) layer. Unlike full frameworks such as Angular, it does not impose routing or state management — those are added with separate packages (e.g. React Router). In practice, the whole ecosystem around React is sometimes called a framework.

### How does React differ from Vue.js?

Both build component-based interfaces on a virtual DOM. React leans on JSX and more freedom (fewer imposed conventions), while Vue offers a more integrated, beginner-friendly toolset. The choice depends on team preference and project scale.

## Related

- [JavaScript](https://nodea.io/en/glossary/javascript)
- [Vue.js](https://nodea.io/en/glossary/vue-js)
- [Angular](https://nodea.io/en/glossary/angular)
- [SPA (Single Page Application)](https://nodea.io/en/glossary/single-page-application)
- [Virtual DOM](https://nodea.io/en/glossary/virtual-dom)

---

Languages: [pl](https://nodea.pl/pl/slownik-pojec/react.md)  
Site index: [llms.txt](https://nodea.io/en/llms.txt)