Your billing zip code, or credit card postal code, is the five-digit number on the bottom right, which in this sample is 90210. This would be the zip code associated with your billing address. It ...

A credit card security code is a three- or four-digit number that’s found only on a physical credit card.

Closely guard your credit card security code unless you are certain that a legitimate business needs it – and only if you initiate a transaction.