Debit cards and credit cards are very different things, functionally, legally, and practically, though they can be implemented similarly on a technical level.

Debit cards and credit cards are very different things, functionally, legally, and practically, though they can be implemented similarly on a technical level. Debit card transactions, legally and financially, withdraw money from the associated bank account at the time of the transaction. The only limit on the amount that can be debited is the amount of money in the associated bank account. If there is insufficient money, the transaction fails. The debit card user is at risk for losses due to fraud or payment disputes. Basically, a debit card is the same as cash but in a convenient thin plastic card form. A credit card transaction, legally and financially, withdraws money from the issuing bank, who then adds that amount to a debt ledger of money owed by the card user to the bank. The transaction only fails if the transaction would exceed an arbitrary credit limit as determined by the bank. The credit card user pays back the debt at the end of the month, or over time, based on the terms of the credit card agreement. The issuing bank is at risk for losses due to fraud or payment disputes. Basically, a credit card is the same as a short-term instantaneous loan agreement, but in the form of a single convenient thing plastic card instead of a dozen or more paper loan agreements.