This triangle-shaped stamp has an unusual purpose

A new U.S. postage stamp is triangle-shaped, and it’s valid on mail sent around the globe to more than 180 countries. The triangle Postcrossing stamp from the U.S. Postal Service commemorates an international pen pal project started in 2005 by Paulo Magalhães, a student in Portugal. The program connects people around the world in a simple but increasingly old-fashioned way: Send a postcard, get one back. What started as a website Magalhães hosted on his personal computer has since sp...