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="VCAT2_AllStudents_DataEntry.png|6" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1" ns="0" title="Main Page" />
      <page pageid="4" ns="0" title="Log in" />
      <page pageid="10" ns="0" title="Viewing Data" />
      <page pageid="24" ns="0" title="Welcome" />
      <page pageid="25" ns="0" title="Selecting Students" />
      <page pageid="211" ns="0" title="Updates" />
      <page pageid="213" ns="0" title="Staff" />
      <page pageid="388" ns="0" title="VCAT Import - Assignments" />
    </pages>
  </query>
</api>