title: What is the difference between xsd and xsi?
body: <p>What exactly is the difference between <strong>XML Schema Document</strong> and <strong>XML Schema Instance</strong> ?</p>
  
  <ul>
  <li><code>xmlns:xsd="http://www.w3.org/2001/XMLSchema"</code></li>
  <li><code>xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"</code></li>
  </ul>
  
  <p>Please elaborate.</p>