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="37" ns="0" title="Combined projections" />
      <page pageid="38" ns="0" title="Composite projections" />
      <page pageid="43" ns="0" title="Conformal projections" />
      <page pageid="44" ns="0" title="Conic projection" />
      <page pageid="45" ns="0" title="Conic projections" />
      <page pageid="50" ns="0" title="Cordiform projections" />
      <page pageid="52" ns="0" title="Cylindric projections" />
      <page pageid="53" ns="0" title="Cylindrical projections" />
    </pages>
  </query>
</api>