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="CP2018.png|20849" />
  </query-continue>
  <query>
    <pages>
      <page pageid="891" ns="0" title="PPI Conference 2011/Board candidatures" />
      <page pageid="1373" ns="3" title="User talk:ThomasG" />
      <page pageid="2212" ns="0" title="PPI Conference 2012/applicants" />
      <page pageid="16783" ns="0" title="PPI Conference 2013/GA meeting/Applicants" />
      <page pageid="20688" ns="0" title="PPI Conference 2015/Board candidatures" />
      <page pageid="20790" ns="0" title="Application from Democratic Pirates of Australia" />
      <page pageid="20849" ns="2" title="User:Numero6" />
    </pages>
  </query>
</api>