title: createElement vs. createElementNS
body: <p>What's the real difference between those two? I mean real, essential difference.
  What's the future holding for regular <code>createElement</code>?</p>
  
  <p>Svg is xml, not html. I get that. So we use <code>createElementNS(ns_string, 'svg')</code>
  And then <code>setAttributeNS(null,,)</code>. Why?
  Why not <code>setAttributeNS('my_ns',,)</code>?</p>
  
  <p>Why must <code>ns_string</code> be <code>http://www.w3.org/2000/svg</code> and not some random string? What's the purpose of a namespace if there is only one namespace?</p>
  
  <p>What's the purpose of <code>ns</code> in regular html? Should I change all instances of <code>createElement</code> to <code>createElementNS</code> in my existing code?</p>
  
  <p>I am reading the <a href="http://www.w3.org/TR/DOM-Level-2-Core/core.html">DOM-Level-2</a> spec. but I'm still puzzled.</p>