A debit card allows you to make payments from a bank account using the amount of cash you have in that account up to any agreed overdraft limit, the amount of the transaction is deducted from the current running balance of the account. A credit card allows you to make payments against an agreed lending limit pre approved with the card issuer, the amount of the transaction is deducted from the "open to buy" balance which is the difference between the debt owed and the credit limit agreed. Both cards use the same infrastructure and card schemes to route the transaction. Credit cards are incorrectly named, the correct terminology should be debt card as spending on the card increases the level of the cardholders debts.