You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allpages apcontinue="Sorter" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="611" ns="0" title="Ball and beam" />
      <p pageid="807" ns="0" title="Ball and beam and distance sensors" />
      <p pageid="790" ns="0" title="Ball and beam and webcam" />
      <p pageid="789" ns="0" title="Ball and beam visual" />
      <p pageid="476" ns="0" title="Dbtest" />
      <p pageid="693" ns="0" title="Inverted pendulum" />
      <p pageid="1586" ns="0" title="Maksim Kavalerov" />
      <p pageid="440" ns="0" title="Mathtest" />
      <p pageid="825" ns="0" title="Robot with wireless computer vision" />
      <p pageid="446" ns="0" title="Smwtest" />
    </allpages>
  </query>
</api>