You mean business or credit card? Credit Cards I believe was embossing, you had the negative of the numbers on the back. They did that because before you had el

You mean business or credit card? Credit Cards I believe was embossing, you had the negative of the numbers on the back. They did that because before you had electronic card readers, merchant were taking credit card payments by making a carbon copy of the credit card number on the invoice: https://en.wikipedia.org/wiki/Credit_card_imprinter https://en.wikipedia.org/wiki/Credit_card_imprinter