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="23" ns="0" title="Bibliography" />
      <p pageid="2" ns="0" title="Bristol: Wikipedia:Community portal" />
      <p pageid="16" ns="0" title="Enterprise Systems Engineering Wiki:Current events" />
      <p pageid="7" ns="0" title="Formal training courses" />
      <p pageid="25" ns="0" title="How to Join" />
      <p pageid="9" ns="0" title="How to join" />
      <p pageid="1" ns="0" title="Main Page" />
      <p pageid="12" ns="0" title="Members Discussion Area" />
      <p pageid="17" ns="0" title="Nature of Enterprise Architecture" />
      <p pageid="5" ns="0" title="New page" />
    </allpages>
  </query>
  <query-continue>
    <allpages apcontinue="Products" />
  </query-continue>
</api>