Ripple is an internet protocol. It's ledger is kept on servers all over. In fact, I am in the process of installing RippleD and connecting my server to the broader network. 

Watch these short youtube videos: 

Here's an [overview of Ripple][1] ... 

Here is an [explanation of Ripple][2] in 60 seconds ... 


  [1]: http://www.youtube.com/watch?v=9zxA3Gt7y3c
  [2]: http://www.youtube.com/watch?v=kwyIEMyMfqs