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>
    <namespaces>
      <ns id="-2" case="first-letter" canonical="Media" xml:space="preserve">Media</ns>
      <ns id="-1" case="first-letter" canonical="Special" xml:space="preserve">Speciale</ns>
      <ns id="0" case="first-letter" content="" xml:space="preserve" />
      <ns id="1" case="first-letter" subpages="" canonical="Talk" xml:space="preserve">Discussione</ns>
      <ns id="2" case="first-letter" subpages="" canonical="User" xml:space="preserve">Utente</ns>
      <ns id="3" case="first-letter" subpages="" canonical="User talk" xml:space="preserve">Discussioni utente</ns>
      <ns id="4" case="first-letter" subpages="" canonical="Project" xml:space="preserve">Documentazione del registro elettronico open source Scuola247</ns>
      <ns id="5" case="first-letter" subpages="" canonical="Project talk" xml:space="preserve">Discussioni Documentazione del registro elettronico open source Scuola247</ns>
      <ns id="6" case="first-letter" canonical="File" xml:space="preserve">File</ns>
      <ns id="7" case="first-letter" subpages="" canonical="File talk" xml:space="preserve">Discussioni file</ns>
      <ns id="8" case="first-letter" subpages="" canonical="MediaWiki" xml:space="preserve">MediaWiki</ns>
      <ns id="9" case="first-letter" subpages="" canonical="MediaWiki talk" xml:space="preserve">Discussioni MediaWiki</ns>
      <ns id="10" case="first-letter" canonical="Template" xml:space="preserve">Template</ns>
      <ns id="11" case="first-letter" subpages="" canonical="Template talk" xml:space="preserve">Discussioni template</ns>
      <ns id="12" case="first-letter" subpages="" canonical="Help" xml:space="preserve">Aiuto</ns>
      <ns id="13" case="first-letter" subpages="" canonical="Help talk" xml:space="preserve">Discussioni aiuto</ns>
      <ns id="14" case="first-letter" canonical="Category" xml:space="preserve">Categoria</ns>
      <ns id="15" case="first-letter" subpages="" canonical="Category talk" xml:space="preserve">Discussioni categoria</ns>
    </namespaces>
  </query>
</api>