That five-digit zip code is one of the key items data brokers use to link a wealth of public records to what you buy. They can figure out whether you’re getting married (or divorced), selling your home, smoke cigarettes, sending a kid off to college or about to have one.
Such information is the cornerstone of a multi-billion dollar industry that enables retailers to target consumers with advertising and coupons. Yet, data privacy experts are concerned about the level at which consumers are being tracked without their knowledge — and what would happen if that data got into the wrong hands.
Source: CNN Money