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>
    <allpages>
      <p pageid="12198" ns="0" title="Change Keyboardlayout in Shell" />
      <p pageid="15" ns="0" title="Choose The Fastest Apt Mirror" />
      <p pageid="12" ns="0" title="Configuration" />
      <p pageid="13" ns="0" title="Enable Autologin" />
      <p pageid="8" ns="0" title="Enable Non-free Repositories" />
      <p pageid="9" ns="0" title="Enabling Non-free Repositories" />
      <p pageid="5" ns="0" title="How to burn image file on a CD/DVD or USB" />
      <p pageid="4" ns="0" title="How to burn image on a CD/DVD or USB" />
      <p pageid="7" ns="0" title="Install Non-free Applications" />
      <p pageid="10" ns="0" title="Installation" />
    </allpages>
  </query>
  <query-continue>
    <allpages apcontinue="Installation_of_a_ATI_graphics_Card" />
  </query-continue>
</api>