The $20 bill is one of the most widely circulated pieces of currency in the United States, yet most people handle it daily without noticing the intricate symbols embedded in its design. These elements are more than just decoration; they are historical markers, symbols...

Every piece of mail, every package delivery, and even modern online shopping depends on five simple numbers. This code seems like just another address detail, but its creation fundamentally changed not only how the nation sends letters but also how it manages commerce and...