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="Compatibilité-des-navigateurs" />
  </query-continue>
  <query>
    <pages>
      <page pageid="2561" ns="0" title="Barre supérieure" />
      <page pageid="2549" ns="0" title="Bibliothèque des rapports" />
      <page pageid="2218" ns="0" title="Bien communiquer avec OpenFlyers" />
      <page pageid="2092" ns="0" title="Bien débuter avec OpenFlyers" />
      <page pageid="2350" ns="0" title="Boîtes de dialogue" />
      <page pageid="2224" ns="0" title="Calendrier" />
      <page pageid="2675" ns="0" title="Carnet de route" />
      <page pageid="2676" ns="0" title="Carnet de vol" />
      <page pageid="2534" ns="0" title="Champs métiers" />
      <page pageid="2827" ns="0" title="Communications" />
    </pages>
  </query>
</api>