Anatomy of a bank card
A rectangle of plastic and a few digits. Let's take it apart, piece by piece.
Two cards in one
Online, three pieces of data do the work: number, date, CVV. The chip, contactless and the PIN work in stores. That is where the card built its security.
Bank cards all share one format: 3.37 × 2.125 inches.
The chip EMV
It computes a unique code for every payment, which makes it very hard to clone.
EMV
The chip standard, named after Europay, Mastercard and Visa, who created it.
Cryptogram
A code made for one payment. Copy it, and it is already useless.
Contactless NFC
Under the surface sits an antenna. Tap the card or phone on the terminal, and it sends a one-time code, just like the chip.
NFC
Near Field Communication: a radio link that only works a few centimeters apart.
The PAN
Primary Account Number: the card number, usually 16 digits and 19 at most. It identifies the issuer and the account. The one drawn here is a public test number.
Check digit
The last digit. A formula called Luhn uses it to catch typos.
The BIN or IIN
The first 6 to 8 digits of the PAN. They tell you which bank issued the card and what type it is: debit, credit, prepaid, corporate.
IIN
Issuer Identification Number: the official name of the BIN.
The expiry date
When the card stops being valid. With the number and the CVV, it completes the trio that does the work online.
The cardholder
The person the card was issued to. Card payments assume that whoever presents the card is that person.
Issuer and network
The issuer is the company behind your card, usually a bank: it approves or declines, debits, and refunds fraud. The network (Visa, Mastercard, Amex, Discover) sets the rules and runs the pipes between banks.
The magnetic stripe
The chip's ancestor, still on many cards as a fallback. Its data never changes, so it is easy to copy. That is skimming.
Skimming
A hidden reader on a terminal or ATM copies the stripe while you pay.
The CVV CVC, CID
The 3 digits on the back (4 on the front of an Amex). PCI DSS forbids storing them after authorization.
CVV, CVC, CID
One code, three names: CVV at Visa, CVC at Mastercard, CID at Amex.
PCI DSS
The security standard for anyone who stores or handles card data.
The PIN
Usually 4 digits, checked by the chip or by the bank, and in the US mostly used on debit cards. It is the only code here that is not written anywhere on the card.
All the pieces
The complete card, laid out on the table.