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="1" ns="0" title="Main Page">
        <revisions>
          <rev user="Tyson Joehler" timestamp="2013-04-23T02:14:08Z" comment="Formatting" />
          <rev user="Tyson Joehler" timestamp="2013-04-23T01:42:38Z" comment="Updated formatting" />
          <rev user="Tyson Joehler" timestamp="2013-04-22T03:00:26Z" comment="Updated link" />
          <rev user="Tyson Joehler" timestamp="2013-04-21T21:28:21Z" comment="Added link" />
          <rev user="Tyson Joehler" timestamp="2013-04-21T16:18:43Z" comment="Added link to new demo page" />
        </revisions>
      </page>
    </pages>
  </query>
  <query-continue>
    <revisions rvcontinue="128" />
  </query-continue>
</api>