Attorney Mike Burns, who represents Michaels Stores Inc. in a ZIP code case, said it's difficult to assess how much each lawsuit could cost each company.

American Express, for example, may prompt you to key in your ZIP code at some stores for security purposes. The information is not kept by the merchant and not used for marketing, the company says.

When retailers ask you for your ZIP code at checkout, it seems innocuous: Maybe they're just trying to see where customers are coming from. Forbes reveals, however, that the five-digit number can ...

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.

Mr. ZIP promoted the use of ZIP codes for the USPS during the 1960s and 1970s. (Photo credit: Wikipedia) ...

Old gas pump in Utah, before the days of automated payment at the pump (photo by Adam Tanner). Recently I wrote an article about why so many stores ask for your ZIP code at check-out. With your ...