They are the five numbers that stand for home. Since 1963, ZIP codes have been a part of just about every piece of mail that travels through our system. But what do those numbers stand for?

ZIP codes were unveiled in 1962, but it was more than 20 years before the U.S. Postal Service announced nearly 100% compliance with the five-digit system.

Why do merchants sometimes ask us for our ZIP code when we buy something? I recently visited the Mob Museum in Las Vegas, an interesting addition to Sin City’s attractions. I paid my admission ...