Node.js is the runtime enviroment of javascript which helps to javascript run outside of the browser..it's open source and cross platfrome (run different operating System like mac window Linux)..

modules are private entity means you do not access their variable and function without permission (using import, export, require funtions) There is two ways you import the module 1) Direct import 2) Object import

There is Two type of modules in NODE JS ....

1. common js module(By default we use it)
2. modern js module (which is use modern framework like React, Angular and others )

A server is just a program that listens for requests from clients (like a browser) and sends back responses.

const http = require("node:http"); // or require("http")

// Create server const server = http.createServer((req, res) => { // req = request object (info from client) // res = response object (we send back info)

res.writeHead(200, { "Content-Type": "text/plain" }); res.end("Hello, World!"); // response body });

// Start listening on port 3000 server.listen(3000, () => { console.log("Server is running at http://localhost:3000/"); });

How it Works

Client Request

You type http://localhost:3000 in your browser.

The browser sends a request (HTTP GET) to your server.

Server Receives Request

http.createServer((req, res) => {...}) runs.

req contains request details (method, URL, headers).

Server Sends Response

res.writeHead(200, {...}) → sets status code and headers.

res.end("Hello, World!") → sends back a message.

Client Displays Response

Your browser shows Hello, World!