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" 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">ex25</ns>
      <ns id="5" case="first-letter" subpages="" canonical="Project talk" xml:space="preserve">ex25 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="100" case="first-letter" canonical="project01" xml:space="preserve">project01</ns>
      <ns id="101" case="first-letter" canonical="project01 talk" xml:space="preserve">project01 talk</ns>
      <ns id="102" case="first-letter" canonical="project02" xml:space="preserve">project02</ns>
      <ns id="103" case="first-letter" canonical="project02 talk" xml:space="preserve">project02 talk</ns>
      <ns id="104" case="first-letter" canonical="project03" xml:space="preserve">project03</ns>
      <ns id="105" case="first-letter" canonical="project03 talk" xml:space="preserve">project03 talk</ns>
      <ns id="106" case="first-letter" canonical="project04" xml:space="preserve">project04</ns>
      <ns id="107" case="first-letter" canonical="project04 talk" xml:space="preserve">project04 talk</ns>
      <ns id="108" case="first-letter" canonical="project05" xml:space="preserve">project05</ns>
      <ns id="109" case="first-letter" canonical="project05 talk" xml:space="preserve">project05 talk</ns>
      <ns id="110" case="first-letter" canonical="project06" xml:space="preserve">project06</ns>
      <ns id="111" case="first-letter" canonical="project06 talk" xml:space="preserve">project06 talk</ns>
      <ns id="112" case="first-letter" canonical="project07" xml:space="preserve">project07</ns>
      <ns id="113" case="first-letter" canonical="project07 talk" xml:space="preserve">project07 talk</ns>
      <ns id="114" case="first-letter" canonical="project08" xml:space="preserve">project08</ns>
      <ns id="115" case="first-letter" canonical="project08 talk" xml:space="preserve">project08 talk</ns>
      <ns id="116" case="first-letter" canonical="project09" xml:space="preserve">project09</ns>
      <ns id="117" case="first-letter" canonical="project09 talk" xml:space="preserve">project09 talk</ns>
      <ns id="118" case="first-letter" canonical="project10" xml:space="preserve">project10</ns>
      <ns id="119" case="first-letter" canonical="project10 talk" xml:space="preserve">project10 talk</ns>
      <ns id="120" case="first-letter" canonical="project11" xml:space="preserve">project11</ns>
      <ns id="121" case="first-letter" canonical="project11 talk" xml:space="preserve">project11 talk</ns>
      <ns id="122" case="first-letter" canonical="project12" xml:space="preserve">project12</ns>
      <ns id="123" case="first-letter" canonical="project12 talk" xml:space="preserve">project12 talk</ns>
      <ns id="124" case="first-letter" canonical="Msc3workshop1G1" xml:space="preserve">Msc3workshop1G1</ns>
      <ns id="125" case="first-letter" canonical="Msc3workshop1G1 talk" xml:space="preserve">Msc3workshop1G1 talk</ns>
      <ns id="126" case="first-letter" canonical="Msc3workshop1G2" xml:space="preserve">Msc3workshop1G2</ns>
      <ns id="127" case="first-letter" canonical="Msc3workshop1G2 talk" xml:space="preserve">Msc3workshop1G2 talk</ns>
      <ns id="128" case="first-letter" canonical="Msc3workshop1G3" xml:space="preserve">Msc3workshop1G3</ns>
      <ns id="129" case="first-letter" canonical="Msc3workshop1G3 talk" xml:space="preserve">Msc3workshop1G3 talk</ns>
      <ns id="130" case="first-letter" canonical="Msc3workshop1G4" xml:space="preserve">Msc3workshop1G4</ns>
      <ns id="131" case="first-letter" canonical="Msc3workshop1G4 talk" xml:space="preserve">Msc3workshop1G4 talk</ns>
      <ns id="132" case="first-letter" canonical="Msc3workshop1G5" xml:space="preserve">Msc3workshop1G5</ns>
      <ns id="133" case="first-letter" canonical="Msc3workshop1G5 talk" xml:space="preserve">Msc3workshop1G5 talk</ns>
      <ns id="134" case="first-letter" canonical="project18" xml:space="preserve">project18</ns>
      <ns id="135" case="first-letter" canonical="project18 talk" xml:space="preserve">project18 talk</ns>
      <ns id="136" case="first-letter" canonical="Msc1G1" xml:space="preserve">Msc1G1</ns>
      <ns id="137" case="first-letter" canonical="Msc1G1 talk" xml:space="preserve">Msc1G1 talk</ns>
      <ns id="138" case="first-letter" canonical="Msc1G2" xml:space="preserve">Msc1G2</ns>
      <ns id="139" case="first-letter" canonical="Msc1G2 talk" xml:space="preserve">Msc1G2 talk</ns>
      <ns id="140" case="first-letter" canonical="Msc1G3" xml:space="preserve">Msc1G3</ns>
      <ns id="141" case="first-letter" canonical="Msc1G3 talk" xml:space="preserve">Msc1G3 talk</ns>
      <ns id="142" case="first-letter" canonical="Msc1G4" xml:space="preserve">Msc1G4</ns>
      <ns id="143" case="first-letter" canonical="Msc1G4 talk" xml:space="preserve">Msc1G4 talk</ns>
      <ns id="144" case="first-letter" canonical="Msc1G5" xml:space="preserve">Msc1G5</ns>
      <ns id="145" case="first-letter" canonical="Msc1G5 talk" xml:space="preserve">Msc1G5 talk</ns>
      <ns id="146" case="first-letter" canonical="Msc1G6" xml:space="preserve">Msc1G6</ns>
      <ns id="147" case="first-letter" canonical="Msc1G6 talk" xml:space="preserve">Msc1G6 talk</ns>
      <ns id="148" case="first-letter" canonical="Msc1G7" xml:space="preserve">Msc1G7</ns>
      <ns id="149" case="first-letter" canonical="Msc1G7 talk" xml:space="preserve">Msc1G7 talk</ns>
      <ns id="150" case="first-letter" canonical="Msc1G8" xml:space="preserve">Msc1G8</ns>
      <ns id="151" case="first-letter" canonical="Msc1G8 talk" xml:space="preserve">Msc1G8 talk</ns>
      <ns id="152" case="first-letter" canonical="Msc1G9" xml:space="preserve">Msc1G9</ns>
      <ns id="153" case="first-letter" canonical="Msc1G9 talk" xml:space="preserve">Msc1G9 talk</ns>
      <ns id="154" case="first-letter" canonical="Msc1G10" xml:space="preserve">Msc1G10</ns>
      <ns id="155" case="first-letter" canonical="Msc1G10 talk" xml:space="preserve">Msc1G10 talk</ns>
      <ns id="156" case="first-letter" canonical="Msc3workshop2G1" xml:space="preserve">Msc3workshop2G1</ns>
      <ns id="157" case="first-letter" canonical="Msc3workshop2G1 talk" xml:space="preserve">Msc3workshop2G1 talk</ns>
      <ns id="158" case="first-letter" canonical="Msc3workshop2G2" xml:space="preserve">Msc3workshop2G2</ns>
      <ns id="159" case="first-letter" canonical="Msc3workshop2G2 talk" xml:space="preserve">Msc3workshop2G2 talk</ns>
      <ns id="160" case="first-letter" canonical="Msc3workshop2G3" xml:space="preserve">Msc3workshop2G3</ns>
      <ns id="161" case="first-letter" canonical="Msc3workshop2G3 talk" xml:space="preserve">Msc3workshop2G3 talk</ns>
      <ns id="162" case="first-letter" canonical="Msc3workshop2G4" xml:space="preserve">Msc3workshop2G4</ns>
      <ns id="163" case="first-letter" canonical="Msc3workshop2G4 talk" xml:space="preserve">Msc3workshop2G4 talk</ns>
      <ns id="164" case="first-letter" canonical="Msc3workshop2G5" xml:space="preserve">Msc3workshop2G5</ns>
      <ns id="165" case="first-letter" canonical="Msc3workshop2G5 talk" xml:space="preserve">Msc3workshop2G5 talk</ns>
      <ns id="310" case="first-letter" canonical="Shared" xml:space="preserve">Shared</ns>
      <ns id="311" case="first-letter" canonical="Shared talk" xml:space="preserve">Shared talk</ns>
    </namespaces>
  </query>
</api>