The earliest music commonly identified as heavy metal came out of the Birmingham area of the United Kingdom in the late 1960s when bands such as Led Zeppelin and Black Sabbath applied an overtly non-traditional approach to blues standards and created new music often based on blues scales and arrangements. These bands were highly influenced by American psychedelic rock musicians including Jimi Hendrix, who had pioneered amplified and processed blues-rock guitar and acted as a bridge between black American music and white European rockers.

Other oft-cited influences include The Who and The Kinks, who had paved the way for heavy metal styles by introducing power chords and more aggressive percussion to the rock genre. Another key influence was Cream, who exemplified the power trio format that would become a staple of heavy metal. Some also cite The Beatles as a key influence; they had increasingly used distortion and heavier arrangements as early as 1967's Sgt. Pepper's Lonely Hearts Club Band. The early heavy metal bands, like Led Zeppelin, Uriah Heep, UFO and Black Sabbath are often called hard rock bands rather than heavy metal, especially those bands whose sound was more similar to traditional rock music. In general, the terms heavy metal and hard rock are often used interchangeably, in particular when discussing the 1970s.

Many such bands are not categorised as "heavy metal bands" as such, but rather as having contributed individual songs or works that contributed to the genre; few would consider Jethro Tull a heavy metal band in any real sense, for example, but few would dispute that their song Aqualung was a quintessential early Heavy Metal song. Many people, including Heavy Metal musicians of prominent groups, believe that the foundations of the definite style and sound of pure heavy metal were laid down by Judas Priest (another Birmingham band) with three of their early albums, Sad Wings Of Destiny, Sin After Sin and Stained Class. Although Rainbow are also sometimes cited as pioneering the pure heavy metal genre, although one could also make this claim about the later albums of Deep Purple such as Burn and Stormbringer, these bands are generally considered to be hard rock bands.

The origin of the term heavy metal is uncertain. An early use of the term was by writer William S. Burroughs. In his 1962 novel The Soft Machine, he introduces the character "Uranian Willy, the Heavy Metal Kid". His next novel in, Nova Express, develops this theme further, heavy metal being a metaphor for addictive drugs. The first use of the term "heavy metal" in a song lyric is the words "heavy metal thunder" in the 1968 Steppenwolf song "Born to be Wild":

"I like smoke and lightning
Heavy metal thunder
Racin' with the wind
And the feelin' that I'm under"

The word "heavy" had entered beatnik/counterculture slang some time earlier, and references to "heavy music"-typically slower, more amplified variations of standard pop fare-were already common; indeed, Iron Butterfly first started playing Los Angeles in 1967, their name explained on an album cover, "Iron- symbolic of something heavy as in sound, Butterfly- light, appealing and versatile...an object that can be used freely in the imagination" Iron Butterfly's 1968 debut album was entitled Heavy. The fact that Led Zeppelin incorporated a heavy metal into its name may have sealed the usage of the term.

In the late 1960s, Birmingham, England was still a centre of industry and (given the many rock bands that evolved in and around the city, such as Led Zeppelin, The Move, and Black Sabbath) some people suggest that the term Heavy Metal may have some relation to such activity. Biographies of The Move have claimed that the sound came from their 'heavy' guitar riffs that were popular amongst the 'metal midlands'. The first well-documented usage of the term "heavy metal", referring to a style of music, appears to be the May 1971 issue of Creem, in a review of Sir Lord Baltimore's Kingdom Come. In this review we are told that "Sir Lord Baltimore seems to have down pat most all the best heavy metal tricks in the book". Regardless of its origin, heavy metal may have been used as a jibe initially but was quickly adopted by its believers.

Heavy metal, as an art form, is more than just music; it is as much visual as it is audible. Album covers and stage shows are almost as important to the presentation of the material as the music itself. Thus, through heavy metal, many artists collaborate to produce a menu of experiences in each piece, offering a wider range of experiences to the audience. In this respect, heavy metal becomes perhaps more of a diverse art form than any single form dominated by one method of expression.
Whereas a painting is experienced visually, a symphony experienced audibly, a heavy metal band's "image" and the common theme that binds all their music is expressed in the artwork on the album, the set of the stage, the tone of the lyrics, in addition to the sound of the music. Rock historians tend to find that the influence of Western pop music gives heavy metal its escape-from-reality fantasy side, as an escape from reality through outlandish and fantastic lyrics, while African-American blues gives heavy metal its naked reality side, focusing on loss, depression and loneliness.

If the audio and thematic components of heavy metal are predominantly blues-influenced reality, then the visual component is predominantly pop-influenced fantasy. The themes of darkness, evil, power, and apocalypse are fantastic language components for addressing the reality of life's problems. Further, in reaction to the "peace and love" hippie culture of the 1960s, heavy metal developed as a counterculture, where light is supplanted by darkness, and the happy ending of pop is replaced by the naked reality that things do not always work out in this world. Whilst fans claim that the medium of darkness is not the message, critics have accused the genre of glorifying the negative aspects of reality.
Heavy metal themes are typically graver than the generally airy pop from the 1950s, 1960s and 1970s, focusing on war, nuclear annihilation, environmental issues, political and religious propaganda. Black Sabbath's "War Pigs", Ozzy Osbourne's "Killer of Giants" and Metallica's "...And Justice for All" are examples of serious contributions to the discussion of the state of affairs. The commentary on reality sometimes tends to become over-simplified because the fantastic poetic vocabulary of heavy metal deals primarily with very clear dichotomies of light and dark, hope and despair, good and evil, which do not make much room for complex shades of grey.

Some might differentiate by observing that pure heavy metal does not generally sing about love, while many hair metal songs are focused on love. In some respects, one might argue that the hair metal scene of the 1980s was the logical endpoint of the glitter or glam rock movement of the 1970s; the visual similarities between the two, with the make-up and fanciful costumes, make the argument more compelling. Glitter rock, however, was lyrically focused on sexual ambiguity, free expression and individuality, while hair metal was unambiguously macho and heterosexual, with little room for diversity of political or social opinions. Ultimately, "pure" heavy metal would position itself at the periphery of pop culture, never quite at centre, and metal denizens contend that the move towards the centre was a commercialism that compromised both the artistic integrity of the form and the opportunity for messages to be taken seriously.

The appropriation of classical music by heavy metal typically includes the influence of Bach and Paganini. Though Deep Purple/Rainbow guitarist Ritchie Blackmore had been experimenting with musical figurations borrowed from classical music since the early 1970s, Edward Van Halen's solo on "Eruption" marks an important moment in the development of virtuosity in metal.
Following Van Halen, the "classical" influence in metal guitar during the 1980s actually looked to the early Eighteenth century for its model of speed and technique. Indeed, the late Baroque era of western art music was also frequently interpreted through a gothic lens. For example, "Mr. Crowley," by Ozzy Osbourne and guitarist Randy Rhoads, uses both a pipe organ and Baroque-inspired guitar solos to create a particular mood for Osbourne's lyrics on the legendary occultist Alister Crowley.

Like many other metal guitarists in the 1980s, Rhoads quite earnestly took up the "learned" study of musical theory and helped to solidify the minor industry of guitar tutor magazines that grew up during the decade. In most instances, however, metal musicians who borrowed the technique and rhetoric of art music were not attempting to be classical musicians. An exception can arguably be found in Yngwie Malmsteen, though many argue that his music relies more on virtuosity and the use of classical-sounding elements such as the harmonic minor scale to appear classical without actually being classical.

As heavy metal uses apocalyptic themes and images of power and darkness, the ability to translate verbal ideas into musical ideas that successfully convey the ideas of the words is critical to heavy metal authenticity and credibility. An excellent example of this is the album Powerslave, by Iron Maiden. The cover is of a dramatic Egyptian pyramid scene, and many of the songs on the album have subject matter that requires a sound suggestive of life and death, including the song "The Rime of the Ancient Mariner", based on the poem by Samuel Taylor Coleridge.

The history of heavy metal, from its 1960s precursors to the creation of heavy metal sub-genres of the late 1980s, can be summarized in the following key artists from three main waves of bands that to a large extent came out of Britain: