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>
    <pages>
      <page pageid="13" ns="0" title="Email Obfuscation" />
      <page pageid="12" ns="0" title="File Upload" />
      <page pageid="17" ns="0" title="Google Maps" />
      <page pageid="10" ns="0" title="Group Based Access Control" />
      <page pageid="7" ns="0" title="LDAP authentication" />
      <page pageid="6" ns="0" title="Math formulas" />
      <page pageid="11" ns="0" title="Mediawiki Permissions" />
    </pages>
  </query>
</api>