title: What kind of code is http://ogp.me/ns/fb#
body: <p>I'm not asking what it does, in the sense of, "It makes your Facebook Like button work."</p>
  
  <p>What I am asking is, is this javascript, is it css, or what? It looks like a class. If I wanted to write my own similar file, what extension would I use to name it?</p>
  
  <p>The reason I am asking is I would like to make my own class, for my own widgets, and reference my own class by putting something like xmlns:zz="http://mydomain.com/mylibrary/zz#"</p>