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>
    <allfileusages gafcontinue="Broom-icon.png|1075" />
  </query-continue>
  <query>
    <pages>
      <page pageid="424" ns="0" title="Water Quality Control of the South-to-North Water Diversion (SNWD) Middle Route Project (MRP)" />
      <page pageid="482" ns="0" title="Ilisu Dam Project, Turkey" />
      <page pageid="532" ns="10" title="Template:Cleanup Required box" />
      <page pageid="533" ns="8" title="MediaWiki:Cleanup required box" />
      <page pageid="540" ns="8" title="MediaWiki:Clean up Required" />
      <page pageid="581" ns="0" title="Addressing Declining Groundwater Supply in Umatilla County, Oregon, USA" />
      <page pageid="680" ns="0" title="Indus Waters Treaty" />
      <page pageid="716" ns="0" title="Case Study of Transboundary Dispute Resolution: the Tigris-Euphrates Basin" />
      <page pageid="2203" ns="0" title="Baglihar Hydroelectric Plant - Issue between Pakistan and India" />
      <page pageid="2304" ns="0" title="The Upper Colorado River Endangered Fish Recovery and San Juan River Basin Recovery Implementation Programs" />
    </pages>
  </query>
</api>