Black metal is an extreme heavy metal subgenre characterized by fast tempos, shrieking vocals, tremolo-picked distorted guitars, raw lo-fi production, unconventional song structures, and atmospheric emphasis. It's lyrical themes focus on misanthropy, anti-Christianity, Satanism, and ethnic paganism, with artists typically wearing corpse paint and using pseudonyms.

The "first wave" began with Venom's 1982 album Black Metal, which named the genre, and was developed further by bands like Bathory, Hellhammer, Sodom, and Destruction.
The defining "second wave" emerged in the early 1990s from the Norwegian scene with bands like Mayhem, Darkthrone, Burzum, Immortal, and Emperor, establishing black metal as a distinct genre and inspiring parallel scenes in Finland, Sweden, and the United States.

Death metal is an extreme heavy metal subgenre that emerged in the mid-1980s, characterized by distorted low-tuned guitars with palm muting and tremolo picking, growling vocals, aggressive drumming with double kicks and blast beats. It's lyrics cover violence, politics, religion, philosophy, and science fiction.
Pioneered by bands like Possessed, Death, and Morbid Angel, it evolved from thrash and early black metal, gaining mainstream attention in the late 1980s.

The genre has since diversified into numerous subgenres including melodic death metal, technical death metal, death-doom, deathgrind, and deathcore, each blending death metal's core elements with different musical styles.

Doom metal is an extreme subgenre of heavy metal music that typically uses slower tempos, low-tuned guitars and a much "thicker" or "heavier" sound than other heavy metal genres. Both the music and the lyrics are intended to evoke a sense of despair, dread, and impending doom. The genre is strongly influenced by the early work of Black Sabbath, who formed a prototype for doom metal.
During the first half of the 1980s, a number of bands such as Witchfinder Generaland Pagan Altarfrom England, American bands Pentagram, Saint Vitus, the Obsessed, Trouble, and Cirith Ungol, and Swedish band Candlemassdefined doom metal as a distinct genre.

"HR/HM" is an abbreviation for the musical genres "hard rock/heavy metal."
These two genres are closely related in both sound and their place in musical history, making it difficult to clearly define the boundary between them. For this reason, the two genres are often combined and considered to be a single genre.
The Japanese heavy metal magazine "BURRN!" prefers to use the terms "HM/HR".
A hybrid term, Hard/Heavy, is also rarely used.

Melodic death metal (also referred to as melodeath) combines death metal's aggressive vocals and distorted guitars with highly melodic riffs and solos borrowed from traditional heavy metal. Pioneered by Carcasswith their 1993 album Heartwork, it was further developed by Swedish bands At the Gates, Dark Tranquillity, and In Flamesin the mid-1990s, establishing the influential "Gothenburg metal" scene.
Landmark albums like At the Gates' Slaughter of the Souland In Flames' The Jester Raceheavily influenced North American bands in the 2000s, spawning the term "At the Gatesworship".

The genre gained mainstream popularity in the late 1990s and 2000s with bands like Children of Bodom, Arch Enemy, and Amon Amarthachieving chart success, particularly after In Flames' 2002 album Reroute to Remaindemonstrated the genre's commercial viability.

Sludge metal (also known as sludge doom or simply sludge) is an extreme subgenre of heavy metal music that combines elements of doom metal and hardcore punk. The genre generally includes slow tempos, down-tuned guitars and nihilistic lyrics discussing poverty, drug addiction and pollution.

The sound of sludge metal has its origins in California hardcore punk bands in the early-to-mid-1980s like Black Flag, Flipperand Fang, who began slowing their tempos and embracing the influence of Black Sabbath. This sound was expanded upon by the Melvinstowards the end of the decade and the bands they influenced in both the Seattle grunge scene, and in Louisiana with Eyehategod, Crowbarand Acid Bath. In the 1990s and 2000s, the sound of sludge diversified: bands including Neurosis, Isisand Cult of Lunahelped to pioneer post-metal, while Baronessand Mastodonfused the genre with progressive metal, while Dystopiadid so with crust punk and Griefwith anarcho-punk.

Thrash metal (or simply thrash) is an extreme subgenre of heavy metal music characterized by its overall aggression and fast tempo. The songs usually use fast percussive beats and low-register guitar riffs, overlaid with shredding-style lead guitar work. The genre emerged in the early 1980s as musicians began fusing the double bass drumming and complex guitar stylings of the new wave of British heavy metal (NWOBHM) with the speed and aggression of hardcore punk. Derived genres include crossover thrash (a fusion of thrash and hardcore punk) and black/thrash (a fusion of thrash and black metal).

The genre was commercially successful from approximately 1985 through 1991, bringing prominence to Metallica, Slayer, Megadeth, and Anthrax, all grouped together as the "Big Four" of U.S. thrash metal. Other bands, such as Overkill, Exodus, and Testamentnever achieved the same level of success as the "Big Four", but had also developed a strong following in the metal community.
Some of the most popular international thrash metal bands from this era were Brazil's Sepultura, Canada's Voivodand Annihilator, Switzerland's Coroner, England's Onslaught, and the genre's German "Big Four": Kreator, Destruction, Sodom, and Tankard.

The thrash metal genre had declined in popularity by the mid-1990s, due to the commercial success of numerous genres such as alternative rock and nu metal. In response, some bands either disbanded or moved away from their thrash metal roots and more towards groove metal or alternative metal.
The genre has seen a resurgence in popularity since the 2000s, with the arrival of various bands such as Evile, Havok, Municipal Waste, and Warbringer, who have all been credited for leading the so-called "thrash metal revival" scene.