AC/DC are a hard rock band formed in Sydney, Australia in 1973 by brothers Angus and Malcolm Young. The band are considered pioneers of hard rock, alongside bands such as Led Zeppelin, Deep Purple, and Black Sabbath. Its members, however, have always classified their music as "rock 'n' roll". AC/DC underwent several line-up changes before releasing their first album, High Voltage, in 1975. Membership remained stable until bassist Cliff Williams replaced Mark Evans in 1977. In 1979, the band recorded their highly successful album, Highway to Hell. Lead singer and co-songwriter Bon Scott died on February 19, 1980, after a night of heavy alcohol consumption. The group briefly considered disbanding, but soon ex-Geordie singer Brian Johnson was selected as Scott's replacement. Later that year, the band released their biggest-selling album, Back in Black. The band's next album, For Those About to Rock We Salute You, was also highly successful and was the first hard rock album to reach #1 in the United States. AC/DC declined in popularity, however, soon after the departure of drummer Phil Rudd in 1983. Poor record sales continued until the release of The Razors Edge in 1990. Phil Rudd returned in 1994 and contributed to the band's 1995 album Ballbreaker. Stiff Upper Lip was released in 2000 and was well-received by critics. A new album is expected in 2007. AC/DC have sold more than 150 million albums worldwide, including more than 68 million albums in the US. Back in Black has sold 42 million units worldwide, including 21 million in the U.S., making it the second-highest-selling album ever, and the biggest-selling album by any band. The band are ranked fourth on VH1's 100 Greatest Artists of Hard Rock.