Global Forever Series
On January 28, 2013, the USPS issued the first stamp in its Global Forever Series. These stamps are used on international mail.
Up until the mid-to-late 1800s, mail sent to other countries was regulated by a number of different agreements that were binding only to signing members. Then in 1874, representatives from 22 nations met in Bern, Switzerland to discuss a better system, and to found the General Postal Union (later called the Universal Postal Union).