As the expense of delivering the mail has grown year after year, the U.S. Postal Service introduced the Forever Stamp to reduce the costs of regularly printing stamps that reflected the ever changing postal rates. This type of stamp was first sold in April 2007.
No matter when or at what rate the forever stamp was purchased, it will always be worth the current first class rate, and can always be used to send a first class letter.
Prior to the Forever Stamp, lettered, non-denominated stamps (with no specific value printed on them) were sold during the transition between rates.
A Forever Stamp can be identified by the image of the Liberty Bell, as well as the word "Forever" printed on the stamp.
Consumers no longer need to purchase one- and two-cent stamps to use their supply of older stamps after the new rate takes effect. Instead of decreasing in value over time, a Forever Stamp increases in value.
Between 1974 and June 2009, the first-class postal rate increased 16 times.