The Forever Stamp is a United States Postal Service stamp that will always be valid for first class mail delivery, no matter how the price of a stamp changes. Forever Stamps were first issued as an option for definitive stamps in 2007, and from 2011 onward, all USPS first class stamps are forever stamps. In addition, global rate stamps and postcard rate stamps also function as "forever" stamps for their respective rates. Forever stamps do not display their price/denomination on the stamp, unlike stamps made before the change.
The reason for making the change were the obvious ease and benefit for consumers. Before the change, customers had to buy make-up rate stamps, usually worth one or two cents, to upgrade their old postage. Since many customers had to do this at the same time, post offices could be jammed with people buying make-up postage, often buying sheets that were worth less than 50 cents. This was obviously also a lot of extra work for the postal clerks. The switch over to the Forever Stamps saved the post office and customers a lot of trouble. The only real losers were the philatelists, who lost the fun of chasing after make-up rate stamps.