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="Sustainable_World" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="9" ns="0" title="Bio Fuel Driven Lorries" />
      <p pageid="12" ns="0" title="Cave World" />
      <p pageid="22" ns="0" title="Cave World Political System" />
      <p pageid="23" ns="0" title="Cave World Transportation System" />
      <p pageid="24" ns="0" title="Democracy of the Knowledgable" />
      <p pageid="5" ns="0" title="Low Energy Trains" />
      <p pageid="1" ns="0" title="Main Page" />
      <p pageid="13" ns="0" title="One-World" />
      <p pageid="21" ns="0" title="Orwell&#039;s World" />
      <p pageid="8" ns="0" title="Pedelecs" />
    </allpages>
  </query>
</api>