Millennium is the third studio album (second in the United States) and the first worldwide album by American vocal group Backstreet Boys. It was released on May 18, 1999, by Jive Records. It was a highly anticipated follow-up to both their U.S. self-titled 1997 album and their second released album, Backstreet's Back (1997).
Millennium held the record for most shipments in one year, with 11 million shipments sold in the United States in 1999. It was nominated for five Grammy Awards and became one of the best-selling albums of all time, selling 24 million copies worldwide. The Backstreet Boys promoted Millennium through the Into the Millennium Tour, which became one of the fastest-grossing tours ever.