 Prior to their creation, when the cost to mail a first-class letter increased, people would have to buy one or two-cent stamps, known as top-up stamps, to stick on envelopes to supplement old stamps. Plus, creating forever stamps reduced the need for top-up stamps, which cost more to print than they're worth. Meanwhile, the Postal Service requires the word forever be crossed out whenever the stamp is pictured. This is to prevent counterfeit copies. The stamps you actually purchase don't have a line through the word. Matt Murphy, Fox News.