Credit Cards

Carbon-paper packets

In the early days of credit cards, sales were transacted by using carbon-paper packets that fit into a simple sliding device called a zip-zap machine. The card would be put face-up in the zip-zap, a carbon-paper packet of alternating paper and carbon paper would be placed over it, and the tight-fitting slide would be run over both of them. The pressure of the slide would create an impression of the credit card number on the papers — one for the customer, one for the merchant, one for the merchant’s bank. Today, such transactions are rare; most are handled by electronic card readers that take the card information via its magnetic stripe.