According to NBC News, the postage rate for First Class mail increased to 41 cents on May 14, 2007; this was a 2-cent hike from previous years. NBC News states that this is the year the "forever" stamp was introduced.
A postal customer purchased the "forever" stamp to lock in the 39-cent rate for the postage stamp prior to the 2007 rate increase; a customer can use these stamps forever. As of Jan. 26, 2014, The United States Postal Service, also known as USPS, increased the rate for mailing a 1-ounce First Class letter to 49 cents. This was a 3-cent rate increase from the previous years, notes USPS.