The first stamp was created in Great Britain on May 1, 1840. It wouldn't take long for people to start collecting them. Just one year later, a woman placed an ad in the London Times seeking ...

The "Inverted Jenny," 1918, one of the rarest and most valuable stamps in the world, celebrates the first air mail in the U.S.—by depicting an inadvertently upside-down airplane. Hannah Whitaker ...