HTTPWebServer.js

var http = require ('http');

//createServer takes a callback function, which gets invoked when a request occurs
//the callback function takes in request and response as parameters 
//request (req) represents whats incoming
//response (res) represents the response we are building
http.createServer(function(req, res) {
  
  //build the HTTP response 
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello World');
  
}).listen(1337, '127.0.0.1' );//listen at port 1337 on the localhost

//we can now go to the browser at the localhost:1337 address and send a req
//we then get a 'Hello World' response