We also have a Visa Debit card, it's linked to our regular bank account. Like everyone else has said you can use it where ever you might use a credit card. I have also found that when using the 'credit' function (as we do say when the vet comes to our house) it takes a few days to come out of the account, as Fleur said. This has got us into trouble a number of times! Suddenly the account would drop by a large amount and it would be a purchase from the week before! Now we just keep track of what has yet to come out and we don't get into trouble anymore