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="Bot_detection.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="119" ns="6" title="File:Banner en backend banner.jpg" />
      <page pageid="123" ns="6" title="File:Banner en backend banner new.jpg" />
      <page pageid="120" ns="6" title="File:Banner en backend bannerstatistic.jpg" />
      <page pageid="124" ns="6" title="File:Banner en backend category new.jpg" />
      <page pageid="122" ns="6" title="File:Banner en frontend all banner.jpg" />
      <page pageid="121" ns="6" title="File:Banner en frontend one banner.jpg" />
      <page pageid="106" ns="6" title="File:Be user online en member.jpg" />
      <page pageid="107" ns="6" title="File:Be user online en user.jpg" />
      <page pageid="21" ns="6" title="File:Beginner.png" />
      <page pageid="342" ns="6" title="File:Bom checker er.jpg" />
    </pages>
  </query>
</api>