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="El_ambiente_de_Madrid" />
  </query-continue>
  <query>
    <pages>
      <page ns="0" title="Diff" missing="" />
      <page ns="0" title="Disco de Newton" missing="" />
      <page pageid="1392" ns="0" title="Barbanegra" />
      <page pageid="1162" ns="0" title="Bastilla" />
      <page pageid="1591" ns="0" title="Bernard-René Jordan de Launay" />
      <page pageid="1596" ns="0" title="Campaña de Italia" />
      <page pageid="1402" ns="0" title="Clara Campoamor" />
      <page pageid="1290" ns="0" title="Contraste de la vegetación y la ciudad de Madrid" />
      <page pageid="332" ns="0" title="Disco de Newton. N15" />
      <page pageid="2307" ns="0" title="El GIF animado. N12. 2017" />
    </pages>
  </query>
</api>