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>
    <pages>
      <page pageid="3" ns="0" title="Concerné ou impliqué ?" />
      <page pageid="43" ns="0" title="Création d&#039;une Fondation reconnue d&#039;utilité publique" />
      <page pageid="63" ns="0" title="Financements" />
      <page pageid="21" ns="0" title="Interparadigmatique" />
      <page pageid="35" ns="0" title="Nomologie" />
      <page pageid="10" ns="0" title="Recherche ouverte" />
      <page pageid="7" ns="0" title="Science, Culture et Sapience" />
    </pages>
  </query>
</api>