What goes around the world and stays in the corner?

A stamp goes around the world but stays in the corner. When the proper postage is placed on the upper edge of an envelope, the stamp lets a letter be sent almost anywhere on earth.

The first stamp was introduced in the British Isles in 1840. For a single penny, a half-ounce letter would be delivered anywhere in the realm. The initial stamp, designed by British Postmaster General Sir Rowland Hill, featured the profile of Queen Victoria on a black background. This stamp was quickly nicknamed "Penny Black". By 1847, the U.S. was issuing 5-cent stamps featuring Benjamin Franklin and 10-cent stamps featuring George Washington.