Other electronic payment systems — sometimes referred to as “electronic money” or “e-money” — also are now common. Their goal is to make purchasing simpler. For example, “stored-value” cards let you transfer cash value to a card. They’re commonly used on public transportation, at colleges and universities, at gas stations, and for prepaid telephone use. Many retailers also sell stored-value cards in place of gift certificates. Some stored-value cards work offline, say, to buy a candy bar at a vending machine; others work online, for example, to buy an item from a website; some have both offline and online features. Some cards can be “reloaded” with additional value, at a cash machine; other cards are “disposable” — you throw them away after you use all their value. Some stored-value cards contain computer chips that make them “smart” cards: These cards may act like a credit card as well as a debit card, and also may contain stored value.