WFMY News 2 - You're at the check out counter and the clerk asks for your zip code. Most of us just give it up without even thinking about it. But this might make you think twice.
Our news partner, CNN discovered retailers can find out all sorts of information about you through your five-digit postal code.
If the store has your name and zip code, they can sell your information to a data broker and ask them to match them up. That's all it takes and the retailer could have your home address, email and even your phone number.
But it doesn't stop there. From that information, retailers can learn extremely private details, such as your income or whether you've gone through bankruptcy.
There's a chance you could end up being the target for other marketing campaigns and they can share what they find about you with other retailers too. The worst case scenario is the possibility that some employees make it personal.
"Employees of a store might decide to stalk you or might simply decide you're good looking and show up at your house or call you," warned Chris Hoofnagle, who teaches privacy law at the University of California, Berkley.
Johanna Davis, puts up her guard every time someone asks for her zip code. "I highly regard my privacy and whenever there are those reward programs, I give a fake birthday. And in this case, I could have given them a fake zip code, but why should I have to do that?"
Experts say the practice is not unlike what political targeting groups use to find independent voters in certain zip codes, but those political groups usually do not match names to addresses, like retailers sometimes do.