What is Express.js?

As described perfectly on its home page, Express is a minimal and flexible Node.js web application framework, providing a robust set of features for building single and multi-page, and hybrid web applications. In other words, it provides all of the tools and basic building blocks you need to get a web server up and running by writing very little code. It puts the power to focus on writing your app and not worry about the nuts and bolts that go into making the basic stuff work in your hands.

The Express framework is one of the most popular Node-based web frameworks as well as one of the single most popular packages available in npm.

If you look at a sample piece of code, one of the most basic implementations of Express, you can see how easy it is to get a web server up and running, for example:

var express = require('express'); 
var app = express();  
app.get('/', function(req, res){
   res.send('Hello World'); 
});
app.listen(3300);

The beauty...