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="2dtut_bergkvistliptutorial.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="2604" ns="6" title="File:030 eyeBreakDown.jpg" />
      <page pageid="2656" ns="6" title="File:150px TimSimpson TrimTutorial.jpg" />
      <page pageid="838" ns="6" title="File:20110422 multiply4x.jpg" />
      <page pageid="2573" ns="6" title="File:2d ColorTheory worqx.jpg" />
      <page pageid="619" ns="6" title="File:2dtut FengZhu.png" />
      <page pageid="2570" ns="6" title="File:2dtut ScottRobertson.jpg" />
      <page pageid="1350" ns="6" title="File:2dtut Straub.png" />
      <page pageid="604" ns="6" title="File:2dtut ancientpigface.png" />
      <page pageid="1148" ns="6" title="File:2dtut animemodelsheets.png" />
      <page pageid="605" ns="6" title="File:2dtut babelab.png" />
    </pages>
  </query>
</api>