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="Big_Button" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="956" ns="0" title="BB Arduino Capes" />
      <p pageid="1498" ns="0" title="BL18 ECG Maven" />
      <p pageid="1091" ns="0" title="BLE Bee" />
      <p pageid="347" ns="0" title="BMP085 DIGITAL PRESSURE SENSOR MODULE" />
      <p pageid="302" ns="0" title="BTBee" />
      <p pageid="300" ns="0" title="BTBee Pro" />
      <p pageid="201" ns="0" title="BT BoosterPack" />
      <p pageid="153" ns="0" title="BT Shield (Master Slave)" />
      <p pageid="149" ns="0" title="BT Shield (Slave)" />
      <p pageid="134" ns="0" title="Basic Test/Tutorial for ITEAD WIFI Shield REV2" />
    </allpages>
  </query>
</api>