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>
    <allpages apcontinue="Bandwidth_Control_Via_a_Smart_and/or_Managed_Ethernet_Switch" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="4073" ns="0" title="BARC" />
      <p pageid="3541" ns="0" title="BASIC Interpreter for Linux" />
      <p pageid="4507" ns="0" title="BCD Code" />
      <p pageid="2643" ns="0" title="BIOS" />
      <p pageid="4483" ns="0" title="BLOB Video" />
      <p pageid="2099" ns="0" title="Backitude" />
      <p pageid="69" ns="0" title="Backup The MySQL Database" />
      <p pageid="2187" ns="0" title="Bad Verizon ESN Number" />
      <p pageid="838" ns="0" title="Bakers Pride Pizza Oven Model MO2T" />
      <p pageid="3251" ns="0" title="Balanced Feed Line and Antenna Tuner Impedance" />
    </allpages>
  </query>
</api>