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="Botellón" />
  </query-continue>
  <query>
    <pages>
      <page pageid="575" ns="0" title="Balance térmico" />
      <page pageid="1019" ns="0" title="Balsa separadora" />
      <page pageid="109" ns="0" title="Bandas de octava" />
      <page pageid="347" ns="0" title="Benceno" />
      <page pageid="822" ns="0" title="Biocombustible sólido" />
      <page pageid="821" ns="0" title="Biomasa" />
      <page pageid="623" ns="0" title="Bloque de botellas" />
      <page pageid="279" ns="0" title="Boca de incendio equipada" />
      <page pageid="230" ns="0" title="Boreout" />
      <page pageid="621" ns="0" title="Botella" />
    </pages>
  </query>
</api>