React Essentials

React.js is a JavaScript library for building interactive user interfaces, primarily for single-page applications. Developed by Facebook, it uses a component-based architecture, enabling reusable UI elements. React employs a virtual DOM for efficient rendering, updating only necessary parts of the UI. It follows a declarative programming approach, making code more predictable and easier to debug. React also supports hooks for managing state and side effects without class components. With tools like JSX, React Router, and state management libraries (Redux, Context API), it simplifies frontend development. Its ecosystem includes Next.js for server-side rendering and React Native for mobile apps.