Collectible coins include a variety of types, such as commemorative coins, bullion coins, and proof coins. In the United States, the 25-cent coin, commonly known as the quarter, has featured various designs including state quarters and national park quarters. Proof sets, like the 2023 Proof Set, are limited-edition releases that showcase uncirculated coins with a shiny, mirror-like finish, often appealing to collectors for their quality and aesthetic value. These sets typically include examples of the current circulating coins, making them popular among numismatists.