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="Editor_Settings" />
  </query-continue>
  <query>
    <pages>
      <page pageid="104" ns="10" title="Template:Back" />
      <page pageid="405" ns="10" title="Template:Commands for switching pages" />
      <page pageid="215" ns="10" title="Template:Component card" />
      <page pageid="901" ns="10" title="Template:Connection to iRidium Gate via the Internet" />
      <page pageid="244" ns="10" title="Template:Creation of Graphic Interfaces" />
      <page pageid="108" ns="10" title="Template:Creation of New Projects" />
      <page pageid="197" ns="10" title="Template:Creation of graphic interfaces" />
      <page pageid="929" ns="10" title="Template:Definition" />
      <page pageid="1194" ns="10" title="Template:Download a project" />
      <page pageid="1008" ns="10" title="Template:Download the project" />
    </pages>
  </query>
</api>