Key Features of React:

1. Component-Based Architecture:
   • React is built around components, which are reusable, self-contained units that represent a part of the UI. Components can be as simple as a button or as complex as a full webpage. Each component can have its own state, lifecycle methods, and logic, making the application modular and maintainable.
   • Components can be class-basedor functional (with hooks in functional components).
2. JSX (JavaScript XML):
   • React uses JSX, a syntax extension that allows you to write HTML-like code in JavaScript. JSX makes it easy to create and visualize UI components in your code.
3. const element = <h1>Hello, world!</h1>;
4. Virtual DOM:
   • React uses a Virtual DOM (VDOM) to improve performance. The Virtual DOM is an in-memory representation of the actual DOM. When the state of an object changes, React first updates the Virtual DOM, compares it with the previous version, and then efficiently updates the actual DOM only where necessary (a process called reconciliation). This minimizes reflows and repaints in the browser, enhancing app performance.
5. Unidirectional Data Flow:
   • React enforces one-way data flow, meaning data flows from parent components to child components via props. This makes it easier to track changes in the state and helps manage complex applications more predictably.
   • State management within components is handled by useState(for functional components) or setState (for class components).
6. Hooks:
   • React Hooks are functions that allow you to use state and lifecycle features in functional components. Some commonly used hooks are:
     • useState: Adds state to a functional component.
     • useEffect: Allows you to perform side effects (like fetching data, subscriptions, or DOM manipulation).
     • useContext: Provides a way to share values like themes or user data across components without passing props down manually.

7. React Router:
   • React Router is a popular library for handling navigation in React applications. It enables dynamic routing, allowing different components to be displayed based on the URL, making it ideal for single-page applications.
8. React Developer Tools:
   • The React Developer Tools extension for Chrome and Firefox provides a powerful way to inspect and debug React applications. It allows you to view the component tree, check component states and props, and track performance issues.
9. React Native:
   • React Native allows you to build mobile applications for iOS and Android using React. The syntax and concepts are the same as React.js, but React Native uses native components instead of web-based components.

Basic Structure of a React Application:

A simple React application typically consists of a few main parts:

1. Components: The building blocks of the UI. Each component can have its own state, props, and lifecycle methods.
2. State: Data that changes over time, stored in the component (or globally, using a state management solution like Redux or React Context).
3. Props: Data passed to components from their parent components.
4. JSX: A syntax that combines HTML and JavaScript, used to define the UI layout.