available balance refers to the credit limit of the credit card that has not been used. A credit card, also called a debit card, is a credit certificate issued by a commercial bank or credit card company to qualified consumers. It is in the form of a card with the name of the issuing bank, expiration date, number and cardholder's name printed on the front, and a magnetic stripe and signature strip on the back. Consumers with credit cards can go to the special commercial service department for shopping or spending, and then the bank will settle accounts with merchants and cardholders, and cardholders can overdraw within the prescribed limit.