Most Americans know their ZIP code by heart. They type it into online forms, scribble it on envelopes and memorize it as part of their address. But not everyone knows the original meaning of the term.

Add Yahoo as a preferred source to see more of our stories on Google. Most Americans know their ZIP code by heart. They type it into online forms, scribble it on envelopes and memorize it as part of ...

It's very easy to chalk up certain facets of our lives to just being "the way it's always been." From daylight savings time to time zones, most of us don't even give a second thought to the meaning ...