Coins are small, flat pieces of metal or plastic that are used primarily as currency. They come in various types, including circulating coins, commemorative coins, and bullion coins, each with its own purpose and design. In the United States, one notable type is the cent, commonly referred to as a penny, which has undergone numerous design changes since its inception. The cent often features prominent figures and symbols significant to American history and culture, making it not only a means of transaction but also a collectible item for numismatists.