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="File_maintenance.pdf" />
  </query-continue>
  <query>
    <pages>
      <page pageid="336" ns="6" title="File:Accounts trn.pdf" />
      <page pageid="368" ns="6" title="File:Appointments trn.pdf" />
      <page pageid="356" ns="6" title="File:Banking trn.pdf" />
      <page pageid="333" ns="6" title="File:Basic features trn.pdf" />
      <page pageid="376" ns="6" title="File:Budget trn.pdf" />
      <page pageid="248" ns="6" title="File:Button image.png" />
      <page pageid="247" ns="6" title="File:Button link.png" />
      <page pageid="344" ns="6" title="File:Crm trn.pdf" />
      <page pageid="352" ns="6" title="File:Customer payments.pdf" />
      <page pageid="334" ns="6" title="File:Employee trn.pdf" />
    </pages>
  </query>
</api>