FOID is just a special ID for buying a gun. You don't have to own a gun to have one, but you do have to have a FOID to buy a gun. You send in your name, address, photo, etc., and they send you back a card. You show the card to buy a gun, instead of your driver's license. I don't believe you need a FOID to shoot, only to own. I think it also satisfies the background check requirement.