title: how does socket.io work?
body: <p>I am using socket.io and it was quick to setup (thanks to examples on their usage page) but i'd like to find out more about what exactly is going on under covers and what's the technology that makes it work. </p>
  
  <p>what are the exact mechanics of socket.io?  </p>
  
  <p>is it on port 80 or a separate one? </p>
  
  <p>does it really stay open or is that part simulated? </p>
  
  <p>is there a way to profile each socket event ? 
  (sort of like using fiddler to see what happens in ajax calls)</p>