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>
    <pages>
      <page pageid="1387" ns="0" title="TMA4260 Industriell statistikk" />
      <page pageid="1435" ns="0" title="TIØ4256 Teknologiledelse 1" />
      <page pageid="1437" ns="0" title="TFY4215 Innføring i kvantefysikk" />
      <page pageid="1459" ns="0" title="TMA4270 Multivariabel analyse" />
      <page pageid="1470" ns="0" title="TBT4100 Biokjemi GK" />
      <page pageid="2314" ns="10" title="Mal:Notis" />
      <page pageid="2315" ns="10" title="Mal:Utgått" />
      <page pageid="2341" ns="0" title="ETH Zurich, Sveits" />
    </pages>
  </query>
</api>