Sometimes referred to as heavy metal, a genre of rock music that developed in the late 1960s and early 1970s. With roots in blues-rock and psychedelic rock, such bands developed a thick, heavy, guitar-and-drums-centred sound, characterised by highly amplified distortion and fast guitar solos.

The electric guitar is historically the key element in metal. Guitars are often played with distortion pedals through heavily overdriven tube amplifiers to create a thick, powerful, 'heavy' sound. In the early 1970s, some popular metal groups such as Judas Priest and Iron Maiden began using 2 or even 3 guitarists sharing the lead and rhythm guitar roles. Guitar solos are a central element of much metal and are often extremely intricate, using sweep-picking, tapping and other advanced techniques for rapid playing.

Metal vocals vary widely in style, from the multioctave, theatrical manner of Iron Maiden's Bruce Dickinson, to the intentionally gruff approach of Motörhead's Lemmy and Metallica's James Hetfield.

The bass guitar plays an important role in most metal bands, providing the low-end sound crucial to making the music 'heavy'. In addition, the bass is often distorted and modified by a variety of effects pedals. Metal bassists frequently use picks instead of their fingers to get a stronger articulation. Metal songs are more likely than those of other rock genres to employ bass solos, particularly in the first few bars.

The drum setup is generally much larger than with other forms of rock music. Aside from the standard toms, bass drum, snare, and hi-hat, ride and crash cymbals, there is often a double bass drum, additional toms and cymbals and other instruments such as a cowbell.

Although early heavy metal bands such as Led Zeppelin, Deep Purple and Black Sabbath 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.

Sales of metal records declined sharply in the late 1970s in the face of punk, disco and more mainstream rock, but a new wave of British metal fused the music with a punk rock sensibility and an increasing emphasis on speed with bands such as Iron Maiden, Motörhead, Saxon and Def Leppard, and new US bands such as Van Halen were emerging.

Metal became broadly popular during the 1980s, when many now-widespread subgenres first evolved. Variations more aggressive and extreme than metal music of the past were mostly restricted to an underground audience, while others, including glam metal (e.g. Bon Jovi and Mötley Crüe), and, to a lesser extent, thrash metal (e.g. Megadeth and Metallica) went on to mainstream commercial success. Some bands such as Guns N' Roses managed to bridge the diverse underground and commercial audiences. Thrash soon began to evolve and split into more extreme metal genres, including death metal (Slayer, Venom), Scandinavian black metal, power metal (DragonForce), progressive metal (Dream Theater), doom metal and gothic metal.

The era of metal's mainstream dominance came to an end in the early 1990s with the emergence of Nirvana and other grunge bands, signalling the popular breakthrough of alternative rock. Grunge bands were influenced by the heavy metal sound, but rejected the excesses of the more popular metal bands. Glam metal fell out of favour thanks not only to the success of grunge, but also because of the growing popularity of the more aggressive sound typified by Metallica. However, the early 1990s also saw the emergence of a new wave of alternative metal or nu metal styles which have further expanded the definition of the genre.

In recent years, metal remains very popular in Europe, especially in Scandinavia and Germany. Metalcore, an originally American hybrid of thrash metal, melodic death metal and hardcore punk, emerged as a commercial force in 2002–3 and there has been something of a traditional heavy metal revival, often referred to as retro-metal.