That 3-digit code on the back of the card...
 

...what is it for? The CVC code is the 4-digit number on the face of the card, but there is a 3-digit sequence after the account number on the signature strip. Just a passing curiosity :)

None of my Amex cards have a 3-digit code on the back ...

When and where has your card been issued ??

US Gold and Blue...I think my old Green had it too. Issued over the last couple of years.

No 3 digit code on the back of the Hilton Honors card.

My Rewards Green card has a 3-digit code, but my Starwood (converted from Blue) does not. All Amex cards, of course, use a 4-digit CID number on the front of the card for "card not present" transactions.

My personal Platinum Delta American Express card has a 3 digit code on the back as does my business platinum American Express card :)

I don't know what it's used for, but I had a retailer want to enter it as the security code (as that is apparently how some Visa/MC's do it). The number on my card had faded too much to read. Since every other retailer had used the 4 digit number on the face, I suggested that this retailer use the 4 digit number, and it worked fine. In speaking with Amex Customer Service later, I mentioned the faded numbers and asked if I needed a new card; the person responded no, that those number are not used by the cardholder or retailers. I still don't know what they are, but apparently they really don't matter to us.

There on my Gold Card, but not on Plat. :confused:

I have the three digit # on my Amex, it used to be a Student Optima but then was "upgraded" to Blue (the clear / opaque card with the "smart chip" on it).

I don't see a 3-digit # on the back of my Plat charge card (expires 2005)...I believe Amex uses the 4-digit number on the front for verification.

The 3-digit number is used on Visa and MC cards for card verification purposes for mail/phone/e-comm transactions. The number is derived from an algorithm using your account number, plus other account data, to ensure that in a card-not-present transaction, the card is valid. If someone gets hold of your account number (e.g. stolen statement, receipt, etc), they cannot provide this number.