title: How to change PHP files in DIV without reloading all page?
body: <p>I know there are some articles about something like this but I can't figure it out. 
  P.S. I'm new in programming so maybe my question is stupid.</p>
  
  <p>All I wan't to do is to change 4 contents inside a  tag with clickable buttons (button1, button2, button3, button4)</p>
  
  <p>When page loads user see only content_1.php.</p>
  
  <pre><code>&lt;div id="content_box"&gt;
  &lt;? 
  include 'content_1.php';
  include 'content_2.php';
  include 'content_3.php';
  include 'content_4.php';
  
  ?&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Maybe somebody can show an example?</p>
  
  <p>Thanks.</p>