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">Special</ns>
      <ns id="0" case="first-letter" subpages="" content="" xml:space="preserve" />
      <ns id="1" case="first-letter" subpages="" canonical="Talk" xml:space="preserve">Talk</ns>
      <ns id="2" case="first-letter" subpages="" canonical="User" xml:space="preserve">User</ns>
      <ns id="3" case="first-letter" subpages="" canonical="User talk" xml:space="preserve">User talk</ns>
      <ns id="4" case="first-letter" subpages="" canonical="Project" xml:space="preserve">Aino wiki</ns>
      <ns id="5" case="first-letter" subpages="" canonical="Project talk" xml:space="preserve">Aino wiki talk</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">File talk</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">MediaWiki talk</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">Template talk</ns>
      <ns id="12" case="first-letter" subpages="" canonical="Help" xml:space="preserve">Help</ns>
      <ns id="13" case="first-letter" subpages="" canonical="Help talk" xml:space="preserve">Help talk</ns>
      <ns id="14" case="first-letter" canonical="Category" xml:space="preserve">Category</ns>
      <ns id="15" case="first-letter" subpages="" canonical="Category talk" xml:space="preserve">Category talk</ns>
      <ns id="1502" case="first-letter" canonical="Blog" xml:space="preserve">Blog</ns>
      <ns id="1503" case="first-letter" canonical="Blog talk" xml:space="preserve">Blog talk</ns>
      <ns id="3010" case="first-letter" subpages="" canonical="Magento" content="" xml:space="preserve">Magento</ns>
      <ns id="3011" case="first-letter" canonical="Magento talk" xml:space="preserve">Magento talk</ns>
      <ns id="3012" case="first-letter" subpages="" canonical="HTML" content="" xml:space="preserve">HTML</ns>
      <ns id="3013" case="first-letter" canonical="HTML talk" xml:space="preserve">HTML talk</ns>
      <ns id="3014" case="first-letter" subpages="" canonical="Linux" content="" xml:space="preserve">Linux</ns>
      <ns id="3015" case="first-letter" canonical="Linux talk" xml:space="preserve">Linux talk</ns>
      <ns id="3016" case="first-letter" subpages="" canonical="Apache" content="" xml:space="preserve">Apache</ns>
      <ns id="3017" case="first-letter" canonical="Apache talk" xml:space="preserve">Apache talk</ns>
      <ns id="3018" case="first-letter" subpages="" canonical="CSS" content="" xml:space="preserve">CSS</ns>
      <ns id="3019" case="first-letter" canonical="CSS talk" xml:space="preserve">CSS talk</ns>
      <ns id="3020" case="first-letter" subpages="" canonical="Wiki" content="" xml:space="preserve">Wiki</ns>
      <ns id="3021" case="first-letter" canonical="Wiki talk" xml:space="preserve">Wiki talk</ns>
      <ns id="3022" case="first-letter" subpages="" canonical="PHP" content="" xml:space="preserve">PHP</ns>
      <ns id="3023" case="first-letter" canonical="PHP talk" xml:space="preserve">PHP talk</ns>
      <ns id="3024" case="first-letter" subpages="" canonical="JQuery" content="" xml:space="preserve">JQuery</ns>
      <ns id="3025" case="first-letter" canonical="JQuery talk" xml:space="preserve">JQuery talk</ns>
      <ns id="3026" case="first-letter" subpages="" canonical="WordPress" content="" xml:space="preserve">WordPress</ns>
      <ns id="3027" case="first-letter" canonical="WordPress talk" xml:space="preserve">WordPress talk</ns>
      <ns id="3028" case="first-letter" subpages="" canonical="NetBeans" content="" xml:space="preserve">NetBeans</ns>
      <ns id="3029" case="first-letter" canonical="NetBeans talk" xml:space="preserve">NetBeans talk</ns>
      <ns id="3030" case="first-letter" subpages="" canonical="Eclipse" content="" xml:space="preserve">Eclipse</ns>
      <ns id="3031" case="first-letter" canonical="Eclipse talk" xml:space="preserve">Eclipse talk</ns>
      <ns id="3034" case="first-letter" subpages="" canonical="PhoneGap" content="" xml:space="preserve">PhoneGap</ns>
      <ns id="3035" case="first-letter" canonical="PhoneGap talk" xml:space="preserve">PhoneGap talk</ns>
      <ns id="3036" case="first-letter" subpages="" canonical="CSharp" content="" xml:space="preserve">CSharp</ns>
      <ns id="3037" case="first-letter" canonical="CSharp talk" xml:space="preserve">CSharp talk</ns>
      <ns id="3038" case="first-letter" subpages="" canonical="NoteAttivitaSviluppo" content="" xml:space="preserve">NoteAttivitaSviluppo</ns>
      <ns id="3039" case="first-letter" canonical="NoteAttivitaSviluppo talk" xml:space="preserve">NoteAttivitaSviluppo talk</ns>
      <ns id="3040" case="first-letter" subpages="" canonical="MySQL" content="" xml:space="preserve">MySQL</ns>
      <ns id="3041" case="first-letter" canonical="MySQL talk" xml:space="preserve">MySQL talk</ns>
      <ns id="3042" case="first-letter" subpages="" canonical="VisualStudio" content="" xml:space="preserve">VisualStudio</ns>
      <ns id="3043" case="first-letter" canonical="VisualStudio talk" xml:space="preserve">VisualStudio talk</ns>
      <ns id="3044" case="first-letter" subpages="" canonical="MSSQL" content="" xml:space="preserve">MSSQL</ns>
      <ns id="3045" case="first-letter" canonical="MSSQL talk" xml:space="preserve">MSSQL talk</ns>
      <ns id="3046" case="first-letter" subpages="" canonical="XDebug" content="" xml:space="preserve">XDebug</ns>
      <ns id="3047" case="first-letter" canonical="XDebug talk" xml:space="preserve">XDebug talk</ns>
      <ns id="3048" case="first-letter" subpages="" canonical="Windows7" content="" xml:space="preserve">Windows7</ns>
      <ns id="3049" case="first-letter" canonical="Windows7 talk" xml:space="preserve">Windows7 talk</ns>
      <ns id="3050" case="first-letter" subpages="" canonical="SWUtility" content="" xml:space="preserve">SWUtility</ns>
      <ns id="3051" case="first-letter" canonical="SWUtility talk" xml:space="preserve">SWUtility talk</ns>
      <ns id="3052" case="first-letter" subpages="" canonical="Oracle" content="" xml:space="preserve">Programmazione</ns>
      <ns id="3053" case="first-letter" subpages="" canonical="Oracle talk" xml:space="preserve">Programmazione Talk</ns>
      <ns id="3054" case="first-letter" subpages="" canonical="MSPowerApp" content="" xml:space="preserve">NavigazioneMarittima</ns>
      <ns id="3055" case="first-letter" subpages="" canonical="MSPowerApp talk" xml:space="preserve">NavigazioneMarittima Talk</ns>
      <ns id="3056" case="first-letter" subpages="" canonical="Java Script" content="" xml:space="preserve">Java Script</ns>
      <ns id="3057" case="first-letter" subpages="" canonical="Java Script Talk" xml:space="preserve">Java Script Talk</ns>
      <ns id="3058" case="first-letter" canonical="Cartografia" content="" xml:space="preserve">Cartografia</ns>
      <ns id="3059" case="first-letter" subpages="" canonical="Cartografia Talk" xml:space="preserve">Cartografia Talk</ns>
      <ns id="3060" case="first-letter" subpages="" canonical="Android" content="" xml:space="preserve">Android</ns>
      <ns id="3061" case="first-letter" subpages="" canonical="Android Talk" xml:space="preserve">Android Talk</ns>
    </namespaces>
  </query>
</api>