Collectible coins encompass various types, including historic, commemorative, and error coins. In the context of the United States, some notable collectible coins include the 1814 counterstamped coins, which were altered for circulation or to carry specific messages. The four-dollar coins, though not commonly referenced, encompass specific varieties and designs that may be of interest to collectors. These coins often hold significant value based on their rarity, condition, and historical significance. Collectors often focus on items like these for their numismatic appeal and investment potential.