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="Psu.jpg|862" />
  </query-continue>
  <query>
    <pages>
      <page pageid="12" ns="0" title="Test format" />
      <page pageid="22" ns="0" title="Bespoke web pages" />
      <page pageid="121" ns="0" title="Certificate Services" />
      <page pageid="237" ns="0" title="Drawing Lines" />
      <page pageid="693" ns="0" title="A basic index.html file to collect the username and password and pass to a servlet" />
      <page pageid="757" ns="0" title="Controlling a stepper motor with python" />
      <page pageid="862" ns="0" title="Eero fault" />
    </pages>
  </query>
</api>