The first issue. Credit card installment discount is only offered once, not every time. Credit card, also called debit card, is a credit certificate issued by a commercial bank or credit card company to eligible consumers. Credit cards are generally plastic cards with a special carrier, with a length of 85.60 mm, a width of 53.98 mm and a thickness of 1mm, and the name of the issuer, expiration date, serial number and cardholder are printed on the front.