title: What do the dots mean in relative file path?
body: <p>I am new to programming and learning php on my own. I have two question about the following relative path of a file</p>
  
  <pre><code>$fp = fopen ("$_SERVER[DOCUMENT_ROOT]/../orders/orders.txt", 'w');
  </code></pre>
  
  <p>My questions about the relative path in the code above are that:</p>
  
  <ol>
  <li>What I understand, <code>$_SERVER[DOCUMENT_ROOT]</code> points to the very root directory of the file structure like htdocs, www or public_html on different servers. Please guide if I am understanding it correctly?</li>
  <li>What do the two dots mean in the path above?</li>
  </ol>
  
  <p>Thank You</p>