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="Back_in_the_fight1.png|17256" />
  </query-continue>
  <query>
    <pages>
      <page pageid="529" ns="0" title="Back In Action" />
      <page pageid="805" ns="0" title="Pulse Rifles" />
      <page pageid="1243" ns="0" title="Shaders" />
      <page pageid="5832" ns="0" title="Babylon 9191" />
      <page pageid="5979" ns="0" title="Gallery of Shaders" />
      <page pageid="6382" ns="0" title="B-Line Trauma" />
      <page pageid="7033" ns="6" title="File:B line trauma icon1.jpg" />
      <page pageid="9713" ns="0" title="B-Line" />
      <page pageid="14859" ns="0" title="B-29 Party Favor" />
    </pages>
  </query>
</api>