Def Leppard are a British rock band from Sheffield, England, that emerged in the late 1970s as part of the New Wave of British Heavy Metal.

The music of Def Leppard is a mixture of hard rock, glam rock, AOR, and heavy metal elements. The band has occasionally been associated with the hair metal movement of the 1980s, although its sound is more accurately associated with the contemporary NWOBHM genre of the late 1970s. It is understood that the band consider themselves a hard rock band rather than a metal band, though many people would argue that the terms "rock" and "metal" are rather ambiguous in the first place.

The band's songs generally feature simple guitar hooks and catchy, melodic choruses. The Def Leppard sound is also characterized by its combination of hard rock and polished melodic backing vocals. This approach is very much evident on their first international single, Hello America, which blended the backing vocal style of Queen, with the guitar crunch of Thin Lizzy.

On the 1981 High 'N' Dry release, Def Leppard had incorporated elements of AC/DC's 1980 Back in Black album. This is particularly evident on tracks such as High 'N' Dry, and Let it Go. Since Def Leppard were already fans of AC/DC, it follows that they wanted Mutt Lange to produce their second album.

By the release of the Hysteria record, 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, perhaps even to the point of cliché

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