The 1981 Denver 5-cent nickel is part of the United States coinage system issued by the U.S. Mint. Nickels from this year typically feature the portrait of Thomas Jefferson on the obverse side and Monticello on the reverse. Collectors often seek rolls of these coins for their historical significance and numismatic value. The Denver mint mark indicates that these coins were produced at the Denver Mint facility, which is one of the primary U.S. coin production sites. The popularity of nickels, along with the specific year and mint location, can make these coins desirable among collectors.