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="ABX_Comparator_Setup.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="2663" ns="6" title="File:149003917 1d5dd4d83f m.jpg" />
      <page pageid="5000" ns="6" title="File:150px-Cc-zero.svg.png" />
      <page pageid="4899" ns="6" title="File:1 section one way sync.png" />
      <page pageid="4792" ns="6" title="File:2015-09-02 18.11.55.jpg" />
      <page pageid="3039" ns="6" title="File:250px-Rosegarden screenshot.png" />
      <page pageid="4900" ns="6" title="File:2 one way sync devices.png" />
      <page pageid="4901" ns="6" title="File:3 tasks one way sync.png" />
      <page pageid="10703" ns="6" title="File:48th octave vqt.png" />
      <page pageid="1229" ns="6" title="File:600px-Aacguide AACenc01.png" />
      <page pageid="3040" ns="6" title="File:800px-MusE screenshot.jpg" />
    </pages>
  </query>
</api>