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>
    <links plcontinue="1|14|General_Information" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1" ns="0" title="Main Page">
        <links>
          <pl ns="0" title="Authority Control Client Demographics" />
          <pl ns="0" title="Authority Control Terminology" />
          <pl ns="0" title="Dedupe Profile Guide" />
          <pl ns="0" title="Old Series Processing Table" />
          <pl ns="0" title="Profile Guide" />
          <pl ns="0" title="RDA Profile Guide" />
          <pl ns="0" title="Series Processing Table" />
          <pl ns="14" title="Category:Authority Control" />
          <pl ns="14" title="Category:Authority Control Processing" />
          <pl ns="14" title="Category:Authority Providers" />
        </links>
      </page>
    </pages>
  </query>
</api>