personal identification number

A personal identification number (PIN) 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 (such as a banking card) 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. PINs are most often used for ATMs but are increasingly used at the Point of sale, especially for debit cards. Throughout Europe the traditional in-store credit card signing process is being replaced with a system where 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. Apart from financial uses, GSM mobile phones usually allow the user to enter PIN between 4 and 8 digits length. The PIN is recorded in the SIM card.
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Noun
1. a number you choose and use to gain access to various accounts
(synonym) PIN, PIN number
(hypernym) number, identification number

<security> (PIN, "PIN number") A password, typically four digits entered through a telephone keypad or automatic teller machine.
(1996-11-03)

A numeric code which the cardholder may need to quote for verification of identity. In electronic transactions, it is seen as the equivalent of a signature.

a private access code or password usually used with a credit/debit card.