Collectible coins are items of interest for numismatists and can include a variety of types such as commemorative coins, bullion coins, and historical currency. In the United States, notable examples include the One Dollar coin, which has featured various designs, and the Jefferson Nickel, minted in significant quantities since 1938, with particular attention paid to the 1942 issue due to its wartime modifications. The Philadelphia Mint produced coins, including these Jefferson Nickels, with a distinct "P" mintmark introduced later for identification. Collectors often seek out specific years, mintmarks, and conditions to enhance their collections.