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 gplcontinue="1|0|Differential_Geometry_(subject)" />
  </query-continue>
  <query>
    <pages>
      <page ns="0" title="Algebraic Topology (subject)" missing="" contentmodel="wikitext" pagelanguage="en" />
      <page ns="0" title="Analysis (subject)" missing="" contentmodel="wikitext" pagelanguage="en" />
      <page ns="0" title="Complex Analysis (subject)" missing="" contentmodel="wikitext" pagelanguage="en" />
      <page pageid="102" ns="0" title="Abstract Algebra" contentmodel="wikitext" pagelanguage="en" touched="2015-08-28T16:27:07Z" lastrevid="378" counter="8960" length="88" />
      <page pageid="740" ns="0" title="Abstract Algebra (subject)" contentmodel="wikitext" pagelanguage="en" touched="2018-02-06T22:38:43Z" lastrevid="1750" counter="10025" length="2262" />
      <page pageid="700" ns="0" title="Category Theory (subject)" contentmodel="wikitext" pagelanguage="en" touched="2017-12-15T14:59:07Z" lastrevid="1673" counter="7113" length="1983" />
      <page pageid="771" ns="0" title="Combinatorics (subject)" contentmodel="wikitext" pagelanguage="en" touched="2016-11-13T16:07:32Z" lastrevid="1798" counter="6830" length="708" />
      <page pageid="23" ns="0" title="Compactness" contentmodel="wikitext" pagelanguage="en" touched="2018-07-28T07:20:01Z" lastrevid="1432" counter="60310" length="5172" />
      <page pageid="27" ns="0" title="Continuity definitions are equivalent" contentmodel="wikitext" pagelanguage="en" touched="2017-01-17T12:05:31Z" lastrevid="683" counter="14134" length="2479" />
      <page pageid="191" ns="0" title="Differential Geometry" contentmodel="wikitext" pagelanguage="en" touched="2015-08-23T16:30:37Z" lastrevid="1239" counter="12060" length="183" />
    </pages>
  </query>
</api>