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 ns="0" title="Microsoft Windows" missing="" contentmodel="wikitext" pagelanguage="en" />
      <page ns="0" title="Red link" missing="" contentmodel="wikitext" pagelanguage="en" />
      <page pageid="1451" ns="0" title="Category List" contentmodel="wikitext" pagelanguage="en" touched="2014-01-23T10:53:28Z" lastrevid="2086" counter="4182" length="832" new="" />
      <page pageid="1408" ns="0" title="How to make a website" contentmodel="wikitext" pagelanguage="en" touched="2014-01-27T13:53:14Z" lastrevid="2102" counter="104046" length="4851" />
      <page pageid="1435" ns="0" title="How to use a web browser" contentmodel="wikitext" pagelanguage="en" touched="2011-09-17T13:32:18Z" lastrevid="2083" counter="61454" length="3237" />
      <page pageid="1391" ns="0" title="Internet" contentmodel="wikitext" pagelanguage="en" touched="2010-01-07T17:30:16Z" lastrevid="1656" counter="20200" length="4669" />
      <page pageid="1371" ns="0" title="Site Map" contentmodel="wikitext" pagelanguage="en" touched="2014-01-23T12:31:16Z" lastrevid="2098" counter="98911" length="1544" />
      <page pageid="1369" ns="2" title="User:Michael" contentmodel="wikitext" pagelanguage="en" touched="2013-12-23T10:39:38Z" lastrevid="1993" counter="27184" length="747" />
      <page pageid="1368" ns="14" title="Category:Root" contentmodel="wikitext" pagelanguage="en" touched="2014-01-23T10:53:28Z" lastrevid="1370" counter="2698" length="87" new="" />
    </pages>
  </query>
</api>