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>
    <alllinks galcontinue="Export-generator-4" />
  </query-continue>
  <query>
    <pages>
      <page ns="0" title="En/Main_page" missing="" />
      <page pageid="2077" ns="0" title="CommonFormula" />
      <page pageid="2120" ns="0" title="Database OF21" />
      <page pageid="2152" ns="0" title="Database OF35" />
      <page pageid="2153" ns="0" title="Database description" />
      <page pageid="2159" ns="0" title="Discover OpenFlyers software" />
      <page pageid="1452" ns="0" title="Draft" />
      <page pageid="2122" ns="0" title="Export generator 2.0" />
      <page pageid="2123" ns="0" title="Export generator 2.1" />
      <page pageid="2132" ns="0" title="Export generator 3" />
    </pages>
  </query>
</api>