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>
    <allredirects garcontinue="Behemoth,_a_giant_demon_summoned_forth_by_Iana_stands_here._(undead)" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1575" ns="0" title="Baal-Naygash (undead)" />
      <page pageid="3715" ns="0" title="Barbarian Guild" />
      <page pageid="6391" ns="0" title="Barnum is here, polishing his wares lovingly" />
      <page pageid="6599" ns="0" title="BatMUD" />
      <page pageid="5203" ns="0" title="Battleaxe of the Barbarian Lords" />
      <page pageid="1521" ns="0" title="BayPrixces Condito, Arch Mage and Relic Collector" />
      <page pageid="4339" ns="0" title="BayPrixces Condito, Arch Mage of the Brotherhood of Sorcery" />
      <page pageid="11796" ns="0" title="Bearers of the True Rot" />
      <page pageid="2272" ns="0" title="Beautiful rosary called &#039;Cubido&#039; (holy)" />
      <page pageid="7283" ns="0" title="Beautiful transparent longbow" />
    </pages>
  </query>
</api>