title: Why adding version number to CSS file path?
body: <p>I noticed some websites put the version numbers (especially) in the CSS file path. For example:</p>
  
  <pre><code>&lt;link rel="stylesheet" type="text/css" href="style.css?v=12345678" /&gt;
  </code></pre>
  
  <p>What is the main purpose to put the version number? If the purpose is to remember when the CSS file was updated last time, shouldn't the version number added as a comment inside the CSS file?</p>