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>
    <revisions rvcontinue="12903" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1" ns="0" title="Main Page">
        <revisions>
          <rev user="Danny252" timestamp="2017-06-12T09:13:30Z" comment="Featured article" />
          <rev user="Graham Phillips 110" timestamp="2017-06-09T22:39:43Z" comment="new map" />
          <rev user="Graham Phillips 110" timestamp="2017-06-03T07:13:46Z" comment="Remove line break" />
          <rev user="Graham Phillips 110" timestamp="2017-06-02T20:52:57Z" comment="Featured article" />
          <rev user="Graham Phillips 110" timestamp="2017-06-02T14:40:28Z" comment="Use local map images to speed up page loading" />
        </revisions>
      </page>
    </pages>
  </query>
</api>