Personal Identification Number Definition

A personal identification number is a type of password or pass code used on many electronic information systems including automated teller machines (ATMs). For example, when using an ATM the account holder presents an account card and then validates their identity by punching in a PIN. Thus, a lost-and-found ATM account card is insufficient-by itself-to access the associated account. Account PIN numbers should be kept secret and should never be written down on or near the associated account card.