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>
    <allfileusages gafcontinue="Bildschirmfoto-Info_zu_Energieverwaltung.png|5456" />
  </query-continue>
  <query>
    <pages>
      <page pageid="3668" ns="1" title="Talk:Intel Graphics Media Accelerator 950" />
      <page pageid="4080" ns="0" title="Table of thinkpad-acpi LEDs" />
      <page pageid="4594" ns="10" title="Template:Battery(green)" />
      <page pageid="4596" ns="10" title="Template:Battery(amber)" />
      <page pageid="5456" ns="0" title="Installing FreeBSD 7 (i386) on a ThinkPad T43" />
      <page pageid="6375" ns="2" title="User:Numeric" />
    </pages>
  </query>
</api>