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="Alpha_acid_solubility.gif" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1878" ns="6" title="File:104 Weissbier.png" />
      <page pageid="1879" ns="6" title="File:104 Weissbier thumb.png" />
      <page pageid="1456" ns="6" title="File:3rd stage done.jpg" />
      <page pageid="1457" ns="6" title="File:3rd stage start.jpg" />
      <page pageid="1996" ns="6" title="File:555 internals.gif" />
      <page pageid="1697" ns="6" title="File:Acetic acid disassociation.gif" />
      <page pageid="1917" ns="6" title="File:Acid and alkalinity.gif" />
      <page pageid="1711" ns="6" title="File:Acid malt pH shift.gif" />
      <page pageid="1761" ns="6" title="File:Adding titrant.jpg" />
      <page pageid="1867" ns="6" title="File:Alkalinity for pH change.gif" />
    </pages>
  </query>
</api>