Modern commemorative coins in the United States, officially introduced in 1982, are designed to honor events, individuals, or significant anniversaries. The year 1999 saw the release of notable sets, including coins commemorating the 50th Anniversary of the United Nations and the contributions of American sports legends. These sets typically include silver and gold coins, often carrying unique designs and limited mintage, making them popular among collectors. Collecting modern commemorative coin sets can be a rewarding endeavor, with certain coins appreciating in value due to their rarity and demand.