Def Leppard are a English hard rock band from Sheffield who formed in 1977 as part of the New Wave of British Heavy Metal. Thanks to their classic albums, 1983's Pyromania and 1987's Hysteria, they became one of the top selling rock bands of the 1980s.Their music is a mixture of hard rock, glam rock, and heavy metal elements. The band has occasionally been associated with the pop metal movement of the 1980s, although its sound is more accurately associated with the contemporary New Wave of British Heavy Metal (NWOBHM) genre of the late 1970s. The band's songs generally feature simple guitar hooks and catchy, melodic choruses. Their sound is also characterized by its combination of hard rock and polished melodic backing vocals. By the release of the Hysteria, it was apparent that the band had developed a distinctive, futuristic sound featuring heavily processed drums and effects-laden "space-aged" guitar sounds, overlaid with a layered wall of husky, harmonized vocals. Def Leppard are considered a classic example of the rock sound of the 1980s. Tey are one of only five rock bands with two original albums selling over 10 million copies each in the U.S. The others are The Beatles, Led Zeppelin, Pink Floyd, and Van Halen.