A Credit Card is a payment card issued to a cardholder to enable the cardholder to pay a merchant for goods and services based on the cardholder’s accrued debt, i.e. promise to the card issuer to pay them for the amounts plus the other agreed charges.
The card issuer (usually a bank) grants a line of credit to the cardholder, from which the cardholder can borrow money for payment to a merchant or as a cash advance.
The key difference between a Credit Card and a Debit Card is that when you use a Credit Card, you are spending the bank’s money. When you use a Debit Card, you are spending your money.