An ATM card is any payment card issued by a financial institution that enables a customer to access an automated teller machine (ATM) in order to perform transactions such as deposits, cash withdrawals, obtaining account information, etc. ATM cards are known by a variety of names such as bank card, MAC (money access card), client card, key card or cash card, among others. Most payment cards, such as debit and credit cards can also function as ATM cards, although ATM-only cards are also available. Charge and proprietary cards cannot be used as ATM cards. The use of a credit card to withdraw cash at an ATM is treated differently to a POS transaction, usually attracting interest charges from the date of the cash withdrawal. Interbank networks allow the use of ATM cards at ATMs of private operators and financial institutions other than those of the institution that issued the cards.
ATM cards can also be used on improvised ATMs such as "mini ATMs", merchants' card terminals that deliver ATM features without any cash drawer. These terminals can also be used as cashless scrip ATMs by cashing the receipts they issue at the merchant's point of sale.
The first ATM cards were issued in 1967 by Barclays in London.
The size of ATM cards is 85.60 mm × 53.98 mm (3.370 in × 2.125 in) and rounded corners with a radius of 2.88–3.48 mm, in accordance with ISO/IEC 7810#ID-1, the same size as other payment cards, such as credit, debit and other cards. They also have an embossed bank card number conforming with the ISO/IEC 7812 numbering standard.
All ATM machines, at a minimum, will permit cash withdrawals of customers of the machine's owner (if a bank-operated machine) and for cards that are affiliated with any ATM network the machine is also affiliated. They will report the amount of the withdrawal and any fees charged by the machine on the receipt. Most banks and credit unions will permit routine account-related banking transactions at the bank's own ATM, including deposits, checking the balance of an account, and transferring money between accounts. Some may provide additional services, such as selling postage stamps.