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>
    <alllinks galcontinue="Systemanforderungen" />
  </query-continue>
  <query>
    <pages>
      <page ns="0" title="Domitian" missing="" />
      <page ns="0" title="Liste der römischen Kaiser der Antike" missing="" />
      <page ns="0" title="Lucius Antonius Saturninus" missing="" />
      <page pageid="15" ns="0" title="Datensicherung" />
      <page pageid="39" ns="0" title="Datenübernahme" />
      <page pageid="20" ns="0" title="FAQ" />
      <page pageid="17" ns="0" title="Firma eröffnen" />
      <page pageid="23" ns="0" title="Fragen:Rechnungen" />
      <page pageid="46" ns="0" title="Mehrwertsteuer" />
      <page pageid="38" ns="0" title="Produkt Unterschiede" />
    </pages>
  </query>
</api>