A credit card is a plastic card with a magnetic stripe that holds a machine readable code issued by bank allowing the card holder to purchase goods or services on credit. The card issuer (usually a bank) creates a revolving account and grants a line of credit to the cardholder, from which the card holder can borrow money for payment to a merchant or as a cash advance. As long as you pay back the money you borrowed within the “grace period”, you don’t have to pay extra. If you don’t pay it back in that time period, you’ll have to pay interest — a percentage of the money you owe the bank — on top of what you borrowed. Credit cards are a convenient substitute for cash and an essential component of electronic commerce and internet commerce.