React or React.JS is commonly used for creating complex, single-page web applications, and mobile applications.

React uses a declarative approach to programming, allowing developers to describe how a user interface should look and behave, without worrying about the underlying implementation details. React is based on a component-based architecture, which means that UI elements can be broken down into smaller, reusable pieces, making it easier to manage and scale complex applications.

This books contain Handwritten Notes of React.JS.