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>
    <allpages gapcontinue="Treberbrot" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1570" ns="0" title="Tables for Conversions and Calculations" contentmodel="wikitext" pagelanguage="en" touched="2012-03-09T20:51:19Z" lastrevid="4815" counter="98831" length="3539" />
      <page pageid="1490" ns="0" title="Template" contentmodel="wikitext" pagelanguage="en" touched="2008-04-01T02:13:35Z" lastrevid="1738" counter="8482" length="1304" new="" />
      <page pageid="1606" ns="0" title="The Science of Mashing" contentmodel="wikitext" pagelanguage="en" touched="2009-03-08T04:51:24Z" lastrevid="3260" counter="276415" length="1883" />
      <page pageid="1438" ns="0" title="The Theory of Mashing" contentmodel="wikitext" pagelanguage="en" touched="2009-01-29T04:46:44Z" lastrevid="2987" counter="145649" length="17571" />
    </pages>
  </query>
</api>