React.js is a JavaScript library used for building user interfaces (UI)

React allows us to create reusable UI components.

Features in react js

1. Component-Based Architecture: React applications are built using components - independent, reusable pieces of code that return HTML via a render function. This modular approach enables better code organization, reusability, and maintenance.

2. Virtual DOM: React creates an in-memory data structure cache, computes the resulting differences, and efficiently updates only the changed parts in the browser DOM. This approach significantly improves performance compared to direct DOM manipulation.

3. Unidirectional Data Flow: React follows a one-way data binding model where data flows from parent to child components. This makes the code more predictable and easier to debug.

4. JSX Syntax: You can write HTML-like code inside JavaScript.