Mint sets are government prepared sets that contain one of each coin made at each mint for a given year. If during a certain year cents were made at three mints while dimes were produced at two, the set will contain three cents and two dimes; one from each mint and having that mint mark. The coins are not specially prepared; they are what the mint calls business strikes and just pulled from the production line to be sealed in these sets. They can be one of the easier ways to collect coins and are a popular gift for birthdays and other occasions. Official United States Mint Sets have been produced since 1947.