title: Why pass parameters to CSS and JavaScript link files like src="../cnt.js?ver=4.0"?
body: <p>When I saw many sites' source code, parameters were passed to the linking file (CSS/JavaScript).</p>
  
  <p>In the Stack&nbsp;Overflow source, I got </p>
  
  <pre><code>&lt;script type="text/javascript" src="http://sstatic.net/js/master.js?v=55c7eccb8e19"&gt;&lt;/script&gt; 
  </code></pre>
  
  <p>Why is <code>master.js?v=55c7eccb8e19</code> used?</p>
  
  <p>I am sure that JavaScript/CSS files can't get the parameters.</p>
  
  <p>What is the reason?</p>