Definition of Personal Identification Number (PIN)

numeric identification code used by bank customers when making transactions at a self-service electronic banking terminal, such as an automated teller machine. Also known as an access code or security number. A customer's PIN, a numeric code generally four to six digits in length, is his or her signature when making deposits or withdrawing cash at an ATM, or when transferring funds between accounts in a home banking or telephone bill payment service. PINs are cost effective means ofcustomer identification, although banks continue to experiment with other means, such as signature verification. From a bank security standpoint, PINs pose several problems. Customers who are prone to forgetting their PINs often write their access code on their bank card. Also, the person who successfully uses a PIN to withdraw money from an account may not be the authorized cardholder.