title: var express = require('express'); var app = express(), What is express()?? is it a method or a constructor? Where does it come from
body: <pre><code>var express = require('express'); 
  var app = express();
  </code></pre>
  
  <p>This is how we create an express application. But what is this 'express()'? Is it a method or a constructor? Where does it come from??</p>