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="Change-avatar.jpeg|161" />
  </query-continue>
  <query>
    <pages>
      <page pageid="173" ns="0" title="Enabling ReCaptcha" />
      <page pageid="338" ns="0" title="Event Calendar Distorted" />
      <page pageid="492" ns="0" title="Jomsocial 2 System Requirements" />
      <page pageid="681" ns="0" title="Setup your own server for 5$ a month" />
      <page pageid="812" ns="0" title="Add the custom element based on the Joomla User Group" />
      <page pageid="829" ns="0" title="JS Hello Me" />
      <page pageid="868" ns="0" title="JS Toolbar" />
      <page pageid="869" ns="0" title="JS Birthday" />
    </pages>
  </query>
</api>