What is Node.js?
Node.js is a server-side JavaScript runtime environment built on Google’s V8 JavaScript engine. It uses non-blocking I/O, which means network, file system, or database requests can be processed concurrently. This makes Node.js fast, efficient, and ideal for scalable applications.

🎯 Advantages of Node.js:

• Speed: Thanks to the V8 engine, JavaScript code executes very quickly.

• Asynchronous and event-driven: Can handle many requests simultaneously without waiting.

• Single language – JavaScript: Using one language on both frontend and backend simplifies development.

• Large community and ecosystem: Millions of ready-to-use modules are available through NPM.

• Ideal for real-time applications: Perfect for chat apps, games, and other real-time services.

🔧 How to install Node.js?

For Windows or macOS:

• Visit the official Node.js website.

• Download the installer for your OS.

• Verify installation by running:

• node -v
  npm -v
  

For Linux (Debian/Ubuntu):

sudo apt update

sudo apt install nodejs npm

👨‍💻 Our first Node.js program:

// app.js
const http = require('http');

const server = http.createServer((req, res) => {
  res.end('Hello, Node.js is running!');
});

server.listen(3000, () => {
  console.log('Server started on port 3000');
});

Run it with:

node app.js

Open your browser and go to http://localhost:3000 — you will see the message:
Hello, Node.js is running!

📦 NPM – Node.js package manager

You can easily install libraries with NPM:

npm init -y       # Creates a package.json file
npm install express  # Installs Express.js library

⚙️ Popular Node.js libraries:

📈 Where is Node.js used?

• Web servers (using Express.js)

• RESTful APIs

• Real-time chat applications (Socket.io)

• IoT devices (e.g., Raspberry Pi)

• Serverless functions (AWS Lambda)

• Telegram / Discord bots

🧠 Conclusion:

Node.js is one of the most powerful tools for modern web application development. It allows you to use a single language — JavaScript — on both frontend and backend for efficient development. With libraries like Express.js and Socket.io, Node.js capabilities become even more extensive.