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="Black_Hexorium_Nether_Ore.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="296" ns="6" title="File:1-to-5 Pylon Base.png" />
      <page pageid="297" ns="6" title="File:5-to-1 Pylon Base.png" />
      <page pageid="1607" ns="6" title="File:Advanced Conversion Computer.png" />
      <page pageid="1253" ns="6" title="File:Advanced Rainbow Core.png" />
      <page pageid="1608" ns="6" title="File:Basic Conversion Computer.png" />
      <page pageid="1400" ns="6" title="File:Bg.jpg" />
      <page pageid="51" ns="6" title="File:Black Hexorium Crystal.png" />
      <page pageid="1531" ns="6" title="File:Black Hexorium Dye.png" />
      <page pageid="535" ns="6" title="File:Black Hexorium Monolith.png" />
      <page pageid="536" ns="6" title="File:Black Hexorium Nether Monolith.png" />
    </pages>
  </query>
</api>