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.

Merchants typically use ZIP Codes to determine where their customers live and for other marketing purposes. But beyond that, the information could lead to credit card fraud and identity theft ...

You can't buy a pair of pants without a clerk asking for your ZIP. It turns out stores can do a lot with those five digits, and most of it isn't good.