Yes, everyone gets a sign and sail car of their own. This is your ID for the week and what you use to make puchases. You must put down either cash or a credit card. I can't remember how much cash you need to put down but you can probably find that on Carnivals website. You can choose NOT to give the children charging priveledges by not activating the cards for purchases. They of course, still have to have one for ID puposes. As far as keeping track of the cards, many people bring lanyards and have a hole punched in their card so they can wear them around their neck. Just bring a hole puncher with you or go to the pursers desk and they will do it for you. We did this and no one, including my kids, lost their cards. This amazed me considering just a few months before our cruise we stayed in a hotel in St. Louis for 3 nights and my then 12 y/o daughter lost 3 keys (but she didn't have a lanyard then). If the kids are too young to EVER be anywhere w/o you, then of course, you should carry their cards.