PIN (Personal Identification Number) and PUK (Personal Unblocking Key) are security codes used to protect access to electronic identification documents, such as the Italian Electronic Identity Card (CIE). The PIN is a secret numeric code required to authenticate the cardholder during online identification or digital signature operations. If the PIN is entered incorrectly multiple times, the card becomes locked for security reasons. The PUK is then needed to unlock the card and reset the PIN. Both codes are provided to the cardholder upon issuance of the CIE and must be kept secure to prevent unauthorized access or misuse.