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>
    <allimages gaicontinue="Character_set_-_slot.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="520" ns="6" title="File:51-60 windwalker monk dps rotation.png" />
      <page pageid="193" ns="6" title="File:About Window.gif" />
      <page pageid="515" ns="6" title="File:Advanced power plan settings.png" />
      <page pageid="674" ns="6" title="File:Allods.jpg" />
      <page pageid="392" ns="6" title="File:Arrows.jpg" />
      <page pageid="201" ns="6" title="File:Assist delay.gif" />
      <page pageid="469" ns="6" title="File:AutoAssistingDPSRotation.png" />
      <page pageid="47" ns="6" title="File:Character.png" />
      <page pageid="44" ns="6" title="File:Character set.png" />
      <page pageid="45" ns="6" title="File:Character set - key maps.png" />
    </pages>
  </query>
</api>