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="Allmath2.gif" />
  </query-continue>
  <query>
    <pages>
      <page pageid="27502" ns="6" title="File:02022014 main page BBaJ45001.png" />
      <page pageid="27616" ns="6" title="File:1 Freiburg2013 Plasmid Cas9-VP16.png" />
      <page pageid="27575" ns="6" title="File:20131029170033045749.png" />
      <page pageid="27744" ns="6" title="File:2016igem Team Boston.jpg" />
      <page pageid="27456" ns="6" title="File:240px-Phy2.jpg" />
      <page pageid="27617" ns="6" title="File:2 Freiburg2013 Plasmid Cas9-G9a.png" />
      <page pageid="27618" ns="6" title="File:3 Freiburg 2013 Multiple targeting.png" />
      <page pageid="27731" ns="6" title="File:AAV Gene Therapy.jpg">
        <duplicatefiles>
          <df name="AAV_Gene_Therapy.jpg" user="George Church" timestamp="2012-12-16T02:47:53Z" shared="" />
        </duplicatefiles>
      </page>
      <page pageid="27756" ns="6" title="File:Alignment.png" />
      <page pageid="27599" ns="6" title="File:Allmath.png" />
    </pages>
  </query>
</api>