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="Couple the lake and catchment models" />
          <pl ns="0" title="Develop a computational model for water and carbon isotopes in lake-catchment systems" />
          <pl ns="0" title="Implement the catchment model for North Temperate Lakes" />
          <pl ns="0" title="Implement the lake model for North Temperate Lakes" />
          <pl ns="0" title="Organic Data Science" />
          <pl ns="0" title="Select core lake and catchment models" />
        </links>
      </page>
    </pages>
  </query>
</api>