 Korn are identified as the pioneers of nu metal music , a form of alternative metal music which began in the mid @-@ 1990s . While generally considered an alternative metal and nu metal band , the band has also been labeled as heavy metal , grunge metal , hard rock , rap metal , funk metal , groove metal and industrial metal . Their debut album mixed metal , funk , hip @-@ hop , groove , and dissonance . Their lyrics focus on pain and personal alienation rather than traditional heavy metal themes . In Nu @-@ metal : The Next Generation of Rock & Punk , Korn was marked as the third biggest nu metal band in the world . 
