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>
    <alltransclusions gatcontinue="Cc-by-sa-4.0|1833" />
  </query-continue>
  <query>
    <pages>
      <page pageid="10" ns="0" title="Products of gem-gum-tec" />
      <page pageid="81" ns="0" title="Direct path" />
      <page pageid="261" ns="6" title="File:1024px combustion triangle and replication hexagon.png" />
      <page pageid="304" ns="6" title="File:Truncated octahedron in grid.png" />
      <page pageid="421" ns="6" title="File:Novint Falcon.jpg" />
      <page pageid="427" ns="6" title="File:Pallasite slice-of-Esquel-meteorite.jpg" />
      <page pageid="428" ns="6" title="File:25 solar system objects smaller than Earth.jpg" />
      <page pageid="451" ns="6" title="File:Stone path on Fan Brycheiniog.jpg" />
      <page pageid="452" ns="6" title="File:Rock climber on the Main Wall Trowbarrow.jpg" />
      <page pageid="1569" ns="6" title="File:Structure over Platform of the THSR Taichung Station 02.jpg" />
    </pages>
  </query>
</api>