title: What does the first part of this URL address 'mongodb://localhost:27017/conFusion' do?
body: <p>I am watching a course about using MongoDB in NodeJS applications, this is one line of its codes:</p>
  
  <pre><code>const url = 'mongodb://localhost:27017/conFusion';
  </code></pre>
  
  <p>Then it uses it like this:</p>
  
  <pre><code>MongoClient.connect(url).then((db) =&gt; {
  ...
  }
  </code></pre>
  
  <p>I like to know what is the reason it uses the above address instead of the following?</p>
  
  <pre><code>const url = 'localhost:27017/conFusion';
  </code></pre>
  
  <p>Is there any difference? What is the reason for adding <code>mongodb://</code> in front of the URL address and what does it do?</p>