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>
    <alltransclusions gatcontinue="Chicago|898" />
  </query-continue>
  <query>
    <pages>
      <page pageid="182" ns="0" title="Testing" />
      <page pageid="237" ns="0" title="The Cost of Rights: Why Liberty Depends on Taxes" />
      <page pageid="448" ns="0" title="23 Things They Don&#039;t Tell You About Capitalism" />
      <page pageid="515" ns="4" title="Critiques Of Libertarianism:Current events" />
      <page pageid="668" ns="0" title="Free To Choose" />
      <page pageid="670" ns="0" title="Atlas Shrugged" />
      <page pageid="676" ns="0" title="The Road to Serfdom" />
      <page pageid="677" ns="0" title="Anarchy, State, and Utopia" />
      <page pageid="691" ns="0" title="Defending the Undefendable" />
      <page pageid="2502" ns="10" title="Template:Chart" />
    </pages>
  </query>
</api>