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>
    <allcategories accontinue="깨진_파일_링크가_포함된_문서" />
  </query-continue>
  <query>
    <allcategories>
      <c size="0" pages="0" files="0" subcats="0" xml:space="preserve">K리그 축구단 틀</c>
      <c size="15" pages="15" files="0" subcats="0" xml:space="preserve">RPG만들기2000</c>
      <c size="35" pages="35" files="0" subcats="0" xml:space="preserve">RPG만들기2003</c>
      <c size="4" pages="4" files="0" subcats="0" xml:space="preserve">RPG만들기95</c>
      <c size="6" pages="6" files="0" subcats="0" xml:space="preserve">RPG만들기VX</c>
      <c size="5" pages="5" files="0" subcats="0" xml:space="preserve">RPG만들기XP</c>
      <c size="1" pages="1" files="0" subcats="0" xml:space="preserve">SRPG만들기95</c>
      <c size="1" pages="1" files="0" subcats="0" xml:space="preserve">VNAP</c>
      <c size="121" pages="121" files="0" subcats="0" xml:space="preserve">게임동</c>
      <c size="34" pages="34" files="0" subcats="0" xml:space="preserve">그림동</c>
    </allcategories>
  </query>
</api>