PIN. The first, and most common usage of a PIN is a code used by an individual so that he/she can access his/her bank account at an ATM machine, but others can't. PINs were first used for ATMs in the late 1960s, and have since been applied to many other technological developments in order to keep sensitive information secure. PINs can be used to verify debit card purchases, or as part of a login process for websites, cell phones, or other devices.