1966 U.S. Special Mint Set
A coin set is a collection of high grade coins released by a mint. Among the most popular types of sets are mint sets, which contain uncirculated pieces; proof sets, which include proofs; and year sets, which are issued annually.
Various mints, including the Royal Australian Mint, Royal Canadian Mint, Royal Mint, and the United States Mint, release sets of proof and uncirculated coins every year.
Coins in year sets are sometimes struck in a different way than circulating pieces. For example, each year the Danish National Bank (Danish: Danmarks Nationalbank) issues a set with coins that are "much more clearly embossed than the ordinary coins in circulation".
Sets are typically included with some sort of packaging, such as plastic holders and cases. Paper or cardboard folders were utilized in the past for earlier coin sets, which often led to toning due to the sulfur content of the card.
