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>
    <allimages gaicontinue="Add_a_mail_filter_1.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="76" ns="6" title="File:ACL.png" />
      <page pageid="25976" ns="6" title="File:Accessing online help click help 1.png" />
      <page pageid="25977" ns="6" title="File:Accessing online help click home 1.png" />
      <page pageid="209" ns="6" title="File:Account limits1.png" />
      <page pageid="208" ns="6" title="File:Account overview1.png" />
      <page pageid="77" ns="6" title="File:Actions.png" />
      <page pageid="646" ns="6" title="File:Add Hosted Organization1.png" />
      <page pageid="66" ns="6" title="File:Add New Subdomain - wiki.png" />
      <page pageid="90" ns="6" title="File:Add New Website - wiki.png" />
      <page pageid="998" ns="6" title="File:Add a contact OWA1.png" />
    </pages>
  </query>
</api>