title: What is actually request type 'HEAD' in ajax?
body: <p>In my code, I have got request type <code>HEAD</code> but I actually don't know details about it. The code is like this:</p>
  
  <pre><code>function fileExists(pUrl)
  {
      let fileExist = false;
  
      $.ajax({
          url:pUrl,
          type:'HEAD',
          async:false,
          success: function()
          {
              //file exists
              fileExist = true;
          },
          error: function()
          {
              //file not exists
              fileExist = false;
          }
      });
  
      return fileExist;
  }
  </code></pre>
  
  <p>Can anybody tell me about the <code>HEAD</code>? thanks in advance</p>