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>
    <allpages>
      <p pageid="2343" ns="0" title="Baroque Space Opera" />
      <p pageid="798" ns="0" title="Barre d&#039;outils de page" />
      <p pageid="1494" ns="0" title="Battletech Character Sheet" />
      <p pageid="884" ns="0" title="Beginner&#039;s Guide to GitHub" />
      <p pageid="3310" ns="0" title="Best Practices for Files on Roll20" />
      <p pageid="568" ns="0" title="Black Crusade" />
      <p pageid="735" ns="0" title="Board games" />
      <p pageid="481" ns="0" title="Broadcasting From Google+ Hangouts On Air" />
      <p pageid="2325" ns="0" title="Building Character Sheets" />
      <p pageid="2990" ns="0" title="Building Compendiums" />
    </allpages>
  </query>
  <query-continue>
    <allpages apcontinue="Building_a_dungeon" />
  </query-continue>
</api>