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>
    <pages>
      <page pageid="1" ns="0" title="Main Page">
        <links>
          <pl ns="0" title="Contributors" />
          <pl ns="0" title="Framework Design" />
          <pl ns="0" title="How to use this semantic wiki" />
          <pl ns="0" title="Human Centered Computing to Support Organic Data Science" />
          <pl ns="0" title="What Is Organic Data Science" />
        </links>
      </page>
    </pages>
  </query>
</api>