A number of heavy metal genres have developed since the emergence of heavy metal (often shortened to 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.
Alternative metal is a cross-genre term used to describe heavy metal bands with a pronounced experimental edge. Bands often use typical heavy metal instruments, but include unconventional lyrics, odd time signatures and unusual technique. In many instances it is described as a fusion of metal and alternative rock. Prominent bands in this genre include System of a Down, Tool, Nine Inch Nails and Rage Against the Machine.
Avant-garde metal (sometimes called experimental metal) is a cross-genre term used to describe metal bands that exhibit experimentation through non-standard sounds, instruments, and song structures akin to the genre of metal they are rooted in. Examples include Fantômas, Mr. Bungle and Meshuggah.
Black metal is an extreme subgenre of heavy metal. It often employs fast tempos, shrieked vocals, highly distorted guitars played with tremolo picking in oftentimes droning or hypnotic patterns, and unconventional song structure. It places more emphasis on creating a specific atmosphere of dread or depression than death metal or thrash metal, something it shares with doom metal.
During the first half of the 1980s, certain thrash metal bands established a prototype for black metal. This First Wave includes bands such as Venom, Bathory, Mercyful Fate, Hellhammer and Celtic Frost. A Second Wave emerged in the early 1990s, which consisted primarily of Norwegian bands such as Burzum, Mayhem, Darkthrone, Immortal, Gorgoroth, Satyricon, and Emperor. Black metal can also be combined with Death metal to create Blackened death metal; bands of this subgenre include Behemoth, Zyklon, and Akercocke.
Christian metal is a cross-genre term used to describe metal bands that introduce Christian themes into their lyrics. This sub-genre has a long tradition within metal, starting with Christian hard rock bands springing up alongside the NWOBHM phenomenon to the Christian metalcore bands today. Often the Christian themes are melded with the subjects of the genre the band is rooted in, generally providing a Christian take on the subject matter. Examples include Stryper, Tourniquet, and Mortification.
Crust punk (often simply crust) is one of the evolutions of anarcho-punk and hardcore punk, mixed with extreme metal guitar riffs. The style, which evolved in the mid-1980s in the UK, often had songs with dark, pessimistic lyrics, lingering on political and social ills. It is typically played at a fast tempo with growled and screamed vocals and anarchist lyrics. Notable crust punk bands include Amebix, Antisect, and Doom.
Death metal is an extreme heavy metal subgenre. The genre is typically characterized by the use of heavily distorted guitars, harsh vocals that are low-pitched and/or growled, dark and morbid lyrics, exceptionally fast-paced rhythms and melodies, frequent blast beats on drums, and complex song structures with multiple tempo changes.
Doom metal is an extreme form of heavy metal music during the first half of the 1980s. Generally, doom metal features very slow tempos, low-tuned guitars and a much "denser" or "heavier" sound than other metal genres. Both the music and the lyrics intend to evoke a sense of despair, dread, and impending doom.
Drone metal began as a derivative of doom metal and it is largely defined by drones; notes or chords that are sustained and repeated throughout a piece of music. Typically, the electric guitar is performed with large amounts of reverb and feedback while vocals, if present, are usually growled or screamed. Songs are often very long and lack beat or rhythm in the traditional sense.
Extreme metal is a cross-genre term used to describe heavy metal that is considerably heavier, faster, more aggressive and more abrasive. For example; vocalists may often use death growls or high-pitched shrieks and more obscene lyrics, drummers may often use blast beats, and the band's appearance may be intended to shock.
Folk metal developed in Europe during the 1990s. As the name suggests, the genre is a fusion of heavy metal with folk music. This includes the widespread use of folk instruments and, to a lesser extent, traditional singing styles.
Funk metal is essentially a fusion of heavy metal and funk. It started off in the late eighties as a subgenre of alternative metal, and was heavily influenced by alternative rock bands such as Red Hot Chili Peppers and Fishbone. Funk metal was also one of the key influences of the nu metal genre. Notable funk metal bands include Primus, Living Colour, and Faith No More.
Glam metal (also known as hair metal) is a term used to describe the visual style of certain heavy metal music bands that arose in the late 1970s and early 1980s in the United States, particularly on the Los Angeles Sunset Strip music scene.