Heavy Metal was (arguably) started by Black Sabbath in the late 60s early 70s. Due to an accident that caused guitarist Tony Iommi to lose the tips of his left fingers, he was forced to down tune his guitar which helped create the "heavy" sound that is prominent in heavy metal today. This opened the floodgates and over the years Metal diversified and changed, merging with other genres and evolving to different sub-genres of its own. Here are a few of the main sub-genres.
PIONEERS OF METAL:
While not quite a genre in itself, the Pioneers of metal were the first handful of bands that helped to start heavy metal.
Power metal is usually very (for lack of a better word) epic. Lyrics involving fantasy; vocals with soaring falsettos or operatic wails; melodic guitars with intricate solos. Power Metal can trace its roots to bands like Rainbow and Dio. Later on bands like Iced Earth would incorporate a more aggressive and faster sound that some would call Speed Metal, although some still consider them to be Power Metal.
While some consider this a movement and not a genre at all, I've included it in this list because of the impact on heavy metal as a whole that it had. It stemmed from the massive wave of heavy metal that came from Britain in the late 70s early 80s with classic bands such as Iron Maiden and Judas Priest who would (and continue to) influence nearly every other genre of metal to come. There is not quite a definitive sound that goes along with this genre because so many of the bands sound different. From Motrhead and Venom's punk influence that helped spawn Thrash Metal (and in Venom's case Black metal as well) to Def Leppard's Hair Metal style, to Iron Maiden and Judas Priests almost Power Metal-esque style.
Hair Metal started in the early 80s and was originally influenced by older glam rock bands such as The Sweet and KISS. The style emerged in the Los Angeles Sunset Strip's music scene where the bands would put on extravagant stage shows. They would dress flamboyantly and use lots of hairspray to have their hair in the particular style, which is where the name comes from. Once the bands on the Sunset Strip hit the mainstream market, everybody wanted in on the style, so bands like Poison and Bon Jovi were scrambling to get a piece of the pie that Motley Crue and Ratt were enjoying.
Thrash Metal started in the early 80s with the "Big Four" (Anthrax, Metallica, Megadeth, and Slayer). They took the rawness and speed of hardcore punk and incorporated elements of the NWOBHM. With fast riffs and shredding guitars along with aggressive lyrics and vocals, in many cases dealing with political and social issues, Thrash metal was born.
-At the Gates
Death Metal is one of the most diverse sub-genres of Metal, because there are several sub-sub-genres of death metal. From Melodic Death metal (At the Gates) to Grindcore (Napalm Death) to Blackened Death metal (Behemoth) the list goes on. I'm not going to get into these, but I will cover old school death metal which was started by Death in the mid 80s. Death got their sound from bands like Possessed and Venom along with thrash bands of the current time (like Slayer). Vocals for old school death metal could range from barking to growling to grunting and screaming. With drums that would rival the speed of thrash and eventually surpass it, incorporating blast beats and fast double bass, Death metal took thrash to a new level of aggressive. Death metal usually features fast guitars and complex song structure.
Black metal is probably the most controversial sub-genre of Metal. With harsh shrieks and often graphic lyrics involving Satanic practices (sometimes the lyrics are about Norse Mythology. This branch of Black Metal is called Viking Metal, with bands like Bathory). Black Metal features guitars played with tremolo picking, blast beat drumming, and a very raw recording sound. The term Black Metal was coined by Venom on their album Black Metal. Black Metal is very prominent in Norway where it started in the 80s, but has since expanded to all over the globe.
Folk metal's sound usually depends on the area it is from. For example, Celtic metal bands such as Primordial and Waylander have a distinct sound using pipes and Celtic sounds to incorporate into their classic heavy metal sound. However, Finnish bands such as Finntroll incorporate a Finnish folk music called humppa with death metal, black metal, and classic metal elements. Most Folk metal's sound blends some aspect of their country's folk music with black or death metal.
Progressive Metal (or Prog) is another one of those very diverse sub-genres having many different sounds and styles. Progressive metal uses unique time signatures, intricate and technical instrumentals with varying vocal styles. For example, Cynic incorporates jazz influence with death metal influence, while bands like Dream Theater and Ayreon use power metal incorporated with more technical instrumentation and unique styles of playing, including odd time signatures. Some artists, such as Devin Townsend, blend multiple genres and experiment in varying styles to get a sound that is completely unique and can only be described as Progressive.
Doom metal is also a very diverse genre so I will cover what is commonly called Traditional Doom Metal (Sludge Metal, Stoner Metal, and Drone Metal are three sub-sub-genres influenced by Traditional Doom Metal). Doom metal uses slow tempos, low-tuned guitars, and lyrics that are dark and used to convey despair, dread, and (like it's namesake) doom. They get most of the influence of their sound from Black Sabbath (songs like Into the Void and Black Sabbath).
-As I Lay Dying
-Bring Me the Horizon
Metalcore is currently the most mainstream style of metal. While I personally don't like Metalcore (or it's death metal influenced sub-genre Deathcore) I figured it would only be fair that I include the genre. Metalcore takes elements of extreme metal (death metal, black metal, thrash metal, etc.) and incorporates them with hardcore punk. They are distinguished from thrash because they emphasize the use of breakdowns. Metalcore usually uses screaming vocals as well as clean melodic vocals. Other variations of Metalcore include "Hardcore" (not to be confused with hardcore punk) and Deathcore.
A few genres I didn't cover include:
-Melodic Death Metal (Gothenbug Sound)
-Technical Death Metal
-Brutal Death Metal
-Blackened Death Metal