Personal Identification Number

A personal identification number (PIN, pronounced "pin"; often erroneously PIN number) is a secret numeric password shared between a user and a system that can be used to authenticate the user to the system. Typically, the user is required to provide a non-confidential user identifier or token (the user ID) and a confidential PIN to gain access to the system. Upon receiving the user ID and PIN, the system looks up the PIN based upon the user ID and compares the looked-up PIN with the received PIN. The user is granted access only when the number entered matches with the number stored in the system. Hence, despite the name, a PIN does not personally identify the user.

PINs are most often used for automated teller machines (ATMs) but are increasingly used at the point of sale, for debit cards and credit cards. Throughout Europe and Canada the traditional in-store credit card signing process is increasingly being replaced with a system in which the customer is asked to enter their PIN instead of signing. In the UK and Ireland this goes under the term 'Chip and PIN', since PINs were introduced at the same time as EMV chips on the cards. In other parts of the world, PINs have been used before the introduction of EMV.

In 2006, James Goodfellow, the inventor of the personal identification number, was awarded an OBE in the Queen's Birthday Honours.