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>
    <allfileusages gafcontinue="Shutterstock_102071002.jpg|1146" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1" ns="0" title="Adoption Wiki" />
      <page pageid="1151" ns="0" title="Pregnancy Forums" />
      <page pageid="3320" ns="0" title="Pregnancy Week 3" />
      <page pageid="3368" ns="0" title="Pregnancy Week 42" />
      <page pageid="5760" ns="0" title="Becoming Pregnant" />
      <page pageid="7278" ns="0" title="Maltreatment Statistics" />
      <page pageid="7281" ns="0" title="International Adoption Statistical Charts" />
    </pages>
  </query>
</api>