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="Journal_Citation_Reports" />
  </query-continue>
  <query>
    <pages>
      <page ns="0" title="Encyklopedia" missing="" />
      <page pageid="27" ns="0" title="Doktor" />
      <page pageid="30" ns="0" title="Dom studencki" />
      <page pageid="34" ns="0" title="ECTS (European Credit Transfer and Accumulation System)" />
      <page pageid="35" ns="0" title="Efekty kształcenia" />
      <page pageid="43" ns="0" title="European Reference Index for the Humanities (ERIH)" />
      <page pageid="56" ns="0" title="Fundusz Pomocy Studentom" />
      <page pageid="62" ns="0" title="Impact Factor (IF)" />
      <page pageid="64" ns="0" title="Institute for Scientific Information (ISI)" />
      <page pageid="66" ns="0" title="Jednolite studia magisterskie" />
    </pages>
  </query>
</api>