Collectible coins are numismatic items sought after for their historical significance, rarity, and aesthetic appeal. The 1978 United States dollar coins, produced by the Philadelphia Mint, are part of the larger collection of U.S. coins that may include various denominations, such as one-dollar coins. A roll typically contains 25 coins, and these can be acquired by collectors for their potential investment value or historical interest. Mint marks and condition play a crucial role in determining the collectible value of these coins.