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>
    <pageswithprop gpwpcontinue="1535" />
  </query-continue>
  <query>
    <pages>
      <page pageid="552" ns="0" title="User Guide" contentmodel="wikitext" pagelanguage="en" touched="2016-08-29T13:42:41Z" lastrevid="699" counter="11696" length="5600" new="" />
      <page pageid="553" ns="0" title="Sandbox" contentmodel="wikitext" pagelanguage="en" touched="2016-08-29T18:28:53Z" lastrevid="1455" counter="9625" length="90" />
      <page pageid="1100" ns="10" title="Template:Please leave this line alone and write below (this is the coloured heading)" contentmodel="wikitext" pagelanguage="en" touched="2016-08-29T18:28:17Z" lastrevid="1454" counter="1735" length="613" new="" />
      <page pageid="1332" ns="0" title="On This Day in April" contentmodel="wikitext" pagelanguage="en" touched="2025-02-01T21:38:41Z" lastrevid="2444" counter="3451" length="841" new="" />
      <page pageid="1340" ns="0" title="On This Day in May" contentmodel="wikitext" pagelanguage="en" touched="2024-05-18T19:07:24Z" lastrevid="2489" counter="3119" length="803" new="" />
      <page pageid="1372" ns="0" title="On This Day in June" contentmodel="wikitext" pagelanguage="en" touched="2024-06-17T15:24:05Z" lastrevid="2536" counter="3775" length="810" new="" />
      <page pageid="1406" ns="0" title="On This Day in July" contentmodel="wikitext" pagelanguage="en" touched="2024-01-07T18:37:09Z" lastrevid="2630" counter="3480" length="835" new="" />
      <page pageid="1440" ns="0" title="On This Day in August" contentmodel="wikitext" pagelanguage="en" touched="2024-01-07T18:38:47Z" lastrevid="2707" counter="3206" length="899" new="" />
      <page pageid="1473" ns="0" title="On This Day in September" contentmodel="wikitext" pagelanguage="en" touched="2024-01-07T18:42:19Z" lastrevid="2751" counter="3420" length="965" new="" />
      <page pageid="1503" ns="0" title="On This Day in October" contentmodel="wikitext" pagelanguage="en" touched="2024-01-07T18:47:09Z" lastrevid="2801" counter="3609" length="931" new="" />
    </pages>
  </query>
</api>