title: What does the SVG xmlns attribute do?
body: <p>I've seen source code for embedded SVGs that look like:</p>
  
  <pre><code>&lt;svg&gt;...&lt;/svg&gt;
  </code></pre>
  
  <p>and others that look like:</p>
  
  <pre><code>&lt;svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"&gt;...&lt;/svg&gt;
  </code></pre>
  
  <p>What exactly does specifying the xmlns / xmlns:xlink attributes do?</p>