A number of heavy metal genres have developed since the emergence of heavy metal during the late 1960s and early 1970s. At times, heavy metal genres may overlap or are difficult to distinguish, but they can be identified by a number of traits. They may differ in terms of instrumentation, tempo, song structure, vocal style, lyrics, guitar playing style, drumming style, and so on.

Nu metal is a subgenre of alternative metal that combines elements of heavy metal music with elements of other music genres such as hip hop, funk, industrial, and grunge. Nu metal rarely features guitar solos or other displays of musical technique, and emphasizes rhythm with instrumentation that is heavily syncopated. Nu metal guitarists typically use seven-string guitars that are down-tuned to produce a heavier sound. Vocal styles are often rhythmic and influenced by hip hop, and include singing, rapping, screaming and sometimes growling. DJs are occasionally featured to provide instrumentation such as sampling, turntable scratching and electronic background music. Nu metal is one of the key genres of the new wave of American heavy metal.