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>
    <pages>
      <page ns="0" title="Battery" missing="" />
      <page ns="0" title="Full Wave Rectifier" missing="" />
      <page ns="0" title="Half Wave Rectifier" missing="" />
      <page ns="0" title="Linear DC Voltage Regulator" missing="" />
      <page ns="0" title="Measure an Outlet" missing="" />
      <page ns="0" title="Switched-mode Power Supply" missing="" />
      <page ns="0" title="Unregulated DC Power Supply" missing="" />
      <page pageid="141" ns="0" title="Getting Started" />
      <page pageid="32" ns="0" title="Oscilloscope Models" />
      <page pageid="31" ns="0" title="Reference Sources" />
    </pages>
  </query>
</api>