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="7" ns="0" title="101.1 Hardware-Einstellungen ermitteln und konfigurieren" />
      <page pageid="10" ns="0" title="103.4 Ströme, Pipes und Umleitungen verwenden" />
      <page pageid="13" ns="0" title="105.1 Die Shell-Umgebung anpassen und verwenden" />
      <page pageid="5" ns="0" title="Hauptseite" />
    </pages>
  </query>
</api>