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="Cambiar_grupos_a_los_usuarios_on-fly|1103" />
  </query-continue>
  <query>
    <pages>
      <page pageid="218" ns="0" title="Documentación Educación" />
      <page pageid="278" ns="0" title="Documentación" />
      <page pageid="311" ns="0" title="Documentación de Lihuen 2" />
      <page pageid="402" ns="0" title="Instalando Lihuen 3 en una Exomate Touch" />
      <page pageid="403" ns="10" title="Plantilla:Netbooks" />
      <page pageid="404" ns="0" title="Asus eeepc 1000HE" />
      <page pageid="479" ns="14" title="Categoría:Notebook/Netbook" />
      <page pageid="543" ns="0" title="Wifi lenovo s10e" />
      <page pageid="1354" ns="0" title="Hardware" />
    </pages>
  </query>
</api>