You are looking at the HTML representation of the XML format.
HTML is good for debugging, but probably is not suitable for your application.
See complete documentation, or API help for more information. 
<?xml version="1.0" encoding="utf-8"?>
<api>
  <query>
    <pages>
      <page pageid="100000686" ns="14" title="Category:History Workgroup" touched="2009-11-25T21:35:03Z" lastrevid="100004463" counter="466" length="29" new="" />
      <page pageid="100000621" ns="14" title="Category:Physics Workgroup" touched="2009-11-29T15:15:04Z" lastrevid="100004377" counter="255" length="29" new="" />
      <page pageid="100106610" ns="14" title="Category:Physics Content" touched="2009-11-29T15:15:34Z" lastrevid="100565339" counter="0" length="263" />
      <page pageid="100106850" ns="14" title="Category:History tag" touched="2009-11-28T18:43:48Z" lastrevid="100510899" counter="0" length="223" />
      <page pageid="100083713" ns="14" title="Category:All Content" touched="2009-12-02T21:31:12Z" lastrevid="100603971" counter="1" length="268" />
      <page pageid="100106611" ns="14" title="Category:Physics tag" touched="2009-11-29T15:15:54Z" lastrevid="100510839" counter="0" length="223" />
      <page pageid="100106851" ns="14" title="Category:History Content" touched="2009-11-28T18:43:48Z" lastrevid="100565326" counter="0" length="263" />
    </pages>
  </query>
</api>