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>
    <backlinks gblcontinue="0|Main_Page|105" />
  </query-continue>
  <query>
    <pages>
      <page pageid="3" ns="0" title="Skin Developer" contentmodel="wikitext" pagelanguage="en" touched="2015-04-03T18:27:11Z" lastrevid="67651" counter="" length="8564" />
      <page pageid="4" ns="0" title="Developers FAQ" contentmodel="wikitext" pagelanguage="en" touched="2015-04-03T18:27:11Z" lastrevid="61252" counter="" length="748" />
      <page pageid="5" ns="0" title="Articles" contentmodel="wikitext" pagelanguage="en" touched="2015-04-03T18:27:11Z" lastrevid="61548" counter="" length="1943" />
      <page pageid="6" ns="0" title="Plug-in Developer" contentmodel="wikitext" pagelanguage="en" touched="2015-04-03T18:27:11Z" lastrevid="62206" counter="" length="6324" />
      <page pageid="7" ns="0" title="Visual Developer" contentmodel="wikitext" pagelanguage="en" touched="2015-04-03T18:27:11Z" lastrevid="63977" counter="" length="11348" />
      <page pageid="74" ns="0" title="Modern Skin: Intro" contentmodel="wikitext" pagelanguage="en" touched="2010-12-21T09:24:55Z" lastrevid="61230" counter="" length="2868" />
      <page pageid="75" ns="0" title="Modern Skin: Winamp 2 to W3+" contentmodel="wikitext" pagelanguage="en" touched="2009-07-19T01:41:41Z" lastrevid="59135" counter="" length="1912" />
      <page pageid="83" ns="0" title="Modern Skin: Simple Skin Tutorial" contentmodel="wikitext" pagelanguage="en" touched="2010-11-30T03:32:59Z" lastrevid="61444" counter="" length="2842" />
      <page pageid="84" ns="0" title="Modern Skin: XML Intro" contentmodel="wikitext" pagelanguage="en" touched="2008-09-25T13:06:45Z" lastrevid="929" counter="" length="6216" />
      <page pageid="88" ns="0" title="Modern Skin: Simple Skin Tutorial (Continued)" contentmodel="wikitext" pagelanguage="en" touched="2008-09-25T12:59:48Z" lastrevid="905" counter="" length="9817" />
    </pages>
  </query>
</api>