Noob VPIP Quesion

[P0kerJunkie]

This is probably a dumb question, but I haven't been able to find a useful answer yet. I understand that VP$IP means voluntarily put money in pot, and I understand that it is a very useful statistic, but I don't understand how it is calculated, or how it is expressed. Moreover, I'm not sure what a target VPIP is for TAG player vs a LAG player might be. Sorry for the noob question, but any advice or links to advice would be real helpful. This last one may be unrelated, but I was also wondering what it means if a player is playing "forty four / four", for example. Thanks