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="Hauptseite SS10" touched="2014-02-08T21:17:33Z" lastrevid="3981" counter="63673" length="5735" />
      <page pageid="571" ns="0" title="Hauptseite SoSe 11" touched="2014-02-08T21:17:35Z" lastrevid="8578" counter="172228" length="9785" />
      <page pageid="943" ns="0" title="Hauptseite WS10/11" touched="2014-02-08T21:17:33Z" lastrevid="6423" counter="4560" length="7418" new="" />
      <page pageid="1302" ns="0" title="Hauptseite" touched="2024-04-21T14:08:25Z" lastrevid="40337" counter="1000289" length="14138" />
      <page pageid="1798" ns="0" title="Hauptseite WS 11/12" touched="2014-02-08T21:17:35Z" lastrevid="11211" counter="3419" length="11452" new="" />
      <page pageid="2830" ns="274" title="Widget:Twitter" touched="2014-01-08T18:38:55Z" lastrevid="25696" counter="685" length="1205" />
      <page pageid="3468" ns="12" title="Hilfe:Layout" touched="2014-02-08T21:39:40Z" lastrevid="26118" counter="1752" length="2177" />
      <page pageid="3561" ns="0" title="Hauptseite WS 12/13" touched="2014-02-08T21:17:33Z" lastrevid="22124" counter="1080" length="12880" new="" />
    </pages>
  </query>
</api>