(Heavy) Metal is a genre of rock music that developed in the late 1960s and early 1970s. With roots in blues-rock and psychedelic rock, the bands that created heavy metal developed a thick, heavy, guitar-and-drums-centered sound, characterized by highly amplified distortion and fast guitar solos.

Metal has long had a worldwide following of fans known as "metalheads" or "headbangers". Although early heavy metal bands such as Led Zeppelin, Black Sabbath, and Deep Purple attracted large audiences, they were often critically reviled at the time, a status common throughout the history of the genre. In the mid-1970s, Judas Priest helped spur the genre's evolution by discarding much of its blues influence. The New Wave of British Heavy Metal followed in a similar vein, introducing a punk rock sensibility and an increasing emphasis on speed.

In the mid-1980s, pop-infused glam metal became a major commercial force with groups like Mötley Crüe. Underground scenes produced an array of more extreme, aggressive styles: thrash metal broke into the mainstream with bands such as Metallica, while other styles like death metal and black metal remain subcultural phenomena. Since the mid-1990s, popular styles such as nu metal, which often incorporates elements of funk and hip hop; and metalcore, which blends extreme metal with hardcore punk, have further expanded the definition of the genre.

The typical band lineup includes a drummer, a bassist, a rhythm guitarist, a lead guitarist, and a singer, who may or may not be an instrumentalist. Keyboard instruments are often used to enhance the fullness of the sound.

History

American blues music was a major influence on the early British rockers. Bands like The Rolling Stones and The Yardbirds recorded covers of many classic blues songs, using electric guitar where many of the originals had used acoustic and sometimes speeding up the tempo.

The combination of blues-rock with psychedelic rock formed much of the original basis for heavy metal. One of the most influential bands in forging the merger of genres was the power trio Cream, who derived a massive, heavy sound from unison riffing between guitarist Eric Clapton and bassist Jack Bruce, as well as Ginger Baker's double bass drumming.

In 1968, the sound that would become known as heavy metal began to coalesce. That January, the San Francisco band Blue Cheer released a cover of Eddie Cochran's classic "Summertime Blues" that many consider the first true heavy metal recording. The same month, Steppenwolf released its self-titled debut album, including "Born to Be Wild," with its "heavy metal" lyric.

Led Zeppelin defined central aspects of the emerging genre, with Page's highly distorted guitar style and singer Robert Plant's dramatic, wailing vocals. Other bands, with a more consistently heavy, "purely" metal sound, would prove equally important in codifying the genre. The 1970 releases by Black Sabbath (Black Sabbath and Paranoid) and Deep Purple (Deep Purple in Rock) were crucial in this regard.

On the other side of the Atlantic, the trend-setting group was Grand Funk Railroad, "the most commercially successful American heavy-metal band from 1970 until they disbanded in 1976, they established the Seventies success formula: continuous touring."

Iron Maiden were one of the central bands in the punk rock–inspired New Wave of British Heavy Metal.

Punk rock emerged in the mid-1970s as a reaction against contemporary social conditions as well as what was perceived as the overindulgent, overproduced rock music of the time, including heavy metal. Sales of metal records declined sharply in the late 1970s in the face of punk, disco, and more mainstream rock.

The first generation of metal bands was ceding the limelight. Deep Purple had broken up soon after Blackmore's departure in 1975, and Led Zeppelin folded in 1980. Black Sabbath was routinely upstaged in concert by its opening act, the Los Angeles band Van Halen. Eddie Van Halen established himself as one of the leading metal guitar virtuosos of the era.

Inspired by Van Halen's success, a metal scene began to develop in Southern California, particularly Los Angeles, during the late 1970s. The glam metal movement—along with similarly styled acts such as New York's Twisted Sister—became a major force in metal and the wider spectrum of rock music.

By the mid-1980s, glam metal was a dominant presence on the U.S. charts, music television, and the arena concert circuit. New bands such as L.A.'s Warrant and acts from the East Coast like Poison and Cinderella became major draws, while Mötley Crüe and Ratt remained very popular. Bridging the stylistic gap between hard rock and glam metal, New Jersey's Bon Jovi became enormously successful with its third album, Slippery When Wet (1986).

One band that reached diverse audiences was Guns N' Roses. In contrast to their glam metal contemporaries in L.A., they were seen as much rawer and more dangerous. With the release of their chart-topping Appetite for Destruction (1987), they "recharged and almost single-handedly sustained the Sunset Strip sleaze system for several years."

Many subgenres of metal developed outside of the commercial mainstream during the 1980s: thrash metal, death metal, black metal, power metal, and the related subgenres of doom and gothic metal.

The 1991 release of Forest of Equilibrium, the debut album by UK band Cathedral, helped spark a new wave of doom metal. During the same period, the doom-death fusion style of British bands Paradise Lost, My Dying Bride, and Anathema gave rise to European gothic metal, with its signature dual-vocalist arrangements, exemplified by Norway's Theatre of Tragedy and Tristania.

In the United States, sludge metal, mixing doom and hardcore, emerged in the late 1980s—Eyehategod and Crowbar were leaders in a major Louisiana sludge scene.

The era of metal's mainstream dominance in North America came to an end in the early 1990s with the emergence of Nirvana and other grunge bands, signaling the popular breakthrough of alternative rock.

Glam metal fell out of favor due not only to the success of grunge, but also because of the growing popularity of the more aggressive sound typified by Metallica and the post-thrash groove metal of Pantera and White Zombie.

Like Jane's Addiction, many of the most popular early 1990s groups with roots in heavy metal fall under the umbrella term "alternative metal."

In the mid- and late 1990s came a new wave of U.S. metal groups inspired by the alternative metal bands and their mix of genres. Dubbed "nu metal," bands such as P.O.D., Korn, Papa Roach, Limp Bizkit, Slipknot, and Linkin Park incorporated elements ranging from death metal to hip hop, often including DJs and rap-style vocals.

Metalcore, an originally American hybrid of thrash metal, melodic death metal, and hardcore punk, emerged as a commercial force in 2002–2003. It is rooted in the crossover thrash style developed by bands such as Suicidal Tendencies, Dirty Rotten Imbeciles, and Stormtroopers of Death in the mid-1980s. Through the 1990s, metalcore was mostly an underground phenomenon, but by 2004 it had become popular enough that Killswitch Engage's The End of Heartache and Shadows Fall's The War Within debuted at numbers 21 and 20, respectively, on the Billboard album chart. Bullet for My Valentine, from Wales, reached similar heights on the British album chart with The Poison (2005).

In Europe, especially Germany and Scandinavia, metal continues to be broadly popular. Acts such as the thrash shredding group The Haunted, melodic death metal bands In Flames and Children of Bodom, symphonic extreme metal acts Dimmu Borgir and Cradle of Filth, and power metal group HammerFall have been very successful in recent years.