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>
    <allpages apcontinue="Safety_and_security_at_the_Lab" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="18" ns="0" title="Backups" />
      <p pageid="23" ns="0" title="File and directory permissions and ownership" />
      <p pageid="22" ns="0" title="Guidelines and Terms of use" />
      <p pageid="14" ns="0" title="Hardware resources" />
      <p pageid="11" ns="0" title="Logging in to a terminal session" />
      <p pageid="1" ns="0" title="Main Page" />
      <p pageid="21" ns="0" title="Migrating your data safely" />
      <p pageid="2" ns="0" title="Obtaining an account" />
      <p pageid="25" ns="0" title="Python" />
      <p pageid="12" ns="0" title="Running jobs on our servers" />
    </allpages>
  </query>
</api>