title: PHP file names appending in URL during header() call
body: <p>I have a button on <strong>profile_page.php</strong> called <code>Send Message</code>:</p>
  
  <pre><code>&lt;form method='post'&gt;
     &lt;input type='submit' class='btn btn-info' name='sendmsg' value='Send Message'/&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>And I have the following, simple piece of code which on click the <code>Send Message</code> button, should take them to <code>messages.php/$user</code> - <code>$user</code> being their username:</p>
  
  <pre><code>if (isset($_POST['sendmsg'])){
      header("Location: messages.php?u=$user");
      }
  </code></pre>
  
  <p>Now, when I click <code>Send Message</code> the URL reads </p>
  
  <pre><code>http://localhost/profile_page/messages.php?u=freddy
  </code></pre>
  
  <p>Why is messages.php appending to profile_page.php?</p>