Hailed as the most popular Industrial band of all time, Nine Inch Nails is a rather odd group, as it has only one true member: Trent Reznor. Though supported in concert by a band consisting of regular backup musicians, NIN is Reznor's brainchild, his baby, his masterpiece. It was this, along with its style, that made the band truly unique. Along with bands such as Ministry, they defined both a genre and a musical generation.
Back in the 90s, when other industrial bands were focused on making postmodern-esque electronic noise, Reznor moved to the beat of his own drum, writing melodic and lyrical songs which, while they skirted the edge of pop music, could still be considered to very much keep with the 'industrial' genre. Indeed, one could argue that Reznor was one of the largest influences on the evolution of the Industrial genre during this period.
