Lamarr and Anthiel received a patent in 1941, but the enormous significance of their invention was not realized until decades later. It was first implemented on naval ships during the Cuban Missile Crisis and subsequently emerged in numerous military applications.
Cash back credit card reward programs started out rather simply, offering a flat percentage rate (typically 1 percent of purchases) rebated back to the customer in the form of a check at the end of the year or a statement credit.
1 Debit cards take money out of your checking account immediately.  Debit cards let you get cash quickly. You can use your debit card at an automated teller machine, or ATM, to get money from your checking account. You also can get cash back when you use a debit card to buy something at a store.