Collectible coins refer to various types of coins that are gathered for their value, rarity, or historic significance rather than for everyday currency use. In the United States, coins like the 1-cent denomination, commonly known as pennies, can be particularly collectible, especially those minted in specific years and locations, such as the 1964 Denver mint mark. The 1964 penny is notable for its composition and design, as well as its place in U.S. numismatic history, making it a sought-after item among collectors.