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>
    <allfileusages gafcontinue="DieVecnaDieCover.jpg|589" />
  </query-continue>
  <query>
    <pages>
      <page pageid="22" ns="0" title="Beastlands" />
      <page pageid="28" ns="0" title="Carceri" />
      <page pageid="31" ns="0" title="Baator" />
      <page pageid="35" ns="0" title="Mount Celestia" />
      <page pageid="36" ns="0" title="Bytopia" />
      <page pageid="162" ns="0" title="Chososion" />
      <page pageid="626" ns="0" title="Death knight" />
      <page pageid="649" ns="0" title="Demonomicon of Iggwilv" />
      <page pageid="723" ns="0" title="Ranks of the Baatezu" />
      <page pageid="811" ns="0" title="Civic Festhall" />
    </pages>
  </query>
</api>