Post-metal is a mixture of post-rock and heavy metal, with elements of shoegaze, industrial metal and sludge. It is broadly characterized by distorted guitar, atmospherics, gradual evolution of song structure and a minimal emphasis on vocals. Most songs follow the format of intense crescendos on simple chord sequences but may include sections of powerful riffing.

Hydra Head Records owner and Isis frontman Aaron Turner originally termed the genre "thinking man's metal", demonstrating the link with Avant-garde metal, by trying to move away from common metal conventions. "Post-metal" is the favored name for a growing genre, one also referred to as "instro-metal","postcore", art metal, metal-gaze and a great range of others .

History:

According to Turner, experimental bands such as Flying Luttenbachers, Melvins, Godflesh and Neurosis "laid the groundwork for us we re part of a recognizable lineage". Although Neurosis and Godflesh appeared earlier and display elements befitting post-metal, Isis are often credited with laying down the conventions and definition of the genre in less nebulous terms, with their release of Oceanic in 2002.

Helmet's albums Meantime (1992) and Betty (1994) are cited as having "eschewed the traditional concept of heavy music" and having "trademarked the drop-d power-groove in 5/4." They may be considered "definitive texts in post-metal" though are more accurately described as Alternative Metal/Post-Hardcore; not having much in common with Post-Metal beyond drop tunings.

Post-Metal's history is more closely related to that of Atmospheric Sludge, though some bands are simply Post-Rock with louder guitars.

[The term "post-metal" was earlier used in the UK to describe another emergent genre of metal, at which time the genre now known as "post-metal" was referred to by various other names, most commonly "industrial soundscape music" and "soundscape metal". The term largely fell out of use with the rise of what was known as "post-metal" in the US, effectively seconding the term from the British bands.
Previously, Tool had been labelled as post-metal in 1993 and 1996, as well as in 2006, after the term came into popularity.]

Characteristics:

The simplest way to define post-metal is as a fusion of post-rock and heavy metal. This indicates the interplay of light and dark - taking the distorted guitars and guttural vocals of metal and post-hardcore and setting that against the clean instrumentalism of post-rock. Pieces tend to be at a slow- to mid-tempo, focusing on chord changes and barrages of sound rather than lead guitar riffing and shredding, and usually eschewing guitar solos. Post-metal tends not to feature the dissonance present in the mathcore of Converge and Dillinger Escape Plan.

Isis' Panopticon (2004) is a prime example of post-metal, and post-rock elements are clearly evident in the contrast between calm melodic passages and aggressive distortion-driven climactic sequences. Similar musical structuring can be heard in Pelican's second album released in 2005, The Fire in Our Throats Will Beckon the Thaw, again with a focus on gradual evolution of structure.

Instrumentation:

A typical post-metal set-up includes two or three guitars, a bass guitar, synthesizers, a drum kit and a vocalist. There are a number of completely instrumental post-metal bands, such as Pelican. Orchestral passages are not uncommon, especially in the work of Cult of Luna, Intronaut, and Kayo Dot; other bands such as Boris have music strongly influenced by jazz.

The overall sound is generally very low, with guitars being down tuned sometimes to as low as B, the equivalent of a seven-string guitar. Production is usually very tight, and there is little "garage band" feel to the music. This allows for pervasive or minimalist sections, often including instruments such as clean guitars or synthesizer, to come through more clearly.

Vocals and lyrics:

The general philosophy behind post-metal production is that the whole is greater than the sum of its parts, so each instrument is usually given about equal presence. Vocals are often not particularly high in the mix, and in most cases are "barked" in the style of hardcore or metal, mostly guttural and shouted. Lyrics cover a broad spectrum of issues, usually somewhat metaphysical, existentialist or macroscopic, as opposed to deeply personal or directly allegorical. Themes often include political dissatisfaction, or criticism of herd mentality.

Structure:

Post-metal is also defined by structure, which leans far more towards that of post-rock than metal: songs tend to 'evolve' to a crescendo or climax (or multiple ones within a song), building upon a repeated theme or chord shift, whereas metal, however, often adheres to verse-chorus-verse conventions of song structure. As Aaron Turner of Isis states, "the standard song format of verse-chorus-verse-chorus is something that has been done and redone, and it seems pointless to adhere to that structure when there are so many other avenues to explore". The result of this is often long songs, commonly in the range of six to eleven minutes. Therefore a typical post-metal track is not generally suitable for radio play, nor is it commercially viable. Similarly, albums are often created as quasi-conceptual, creating the greatest impact when listened to as a whole. Likewise, it is not uncommon to see literary influences on albums, such as Red Sparowes' At the Soundless Dawn. This is arguably what makes the genre such an element of the avant-garde. It draws upon the ideas of contemporary classical music and minimalism in the vein of Steve Reich (i.e. repetition and expansion of a theme) and John Cage, at the same time as the metal scene.

A typical post-metal piece might start with a lone guitar, but eventually build to six-plus members playing simultaneously, as shown in songs like "Genesis" from The Beyond by Cult of Luna. Likewise, a post-metal song may leap "head-first" into the music, with distortion and aggression evident from the start. Songs like this challenge the definition of the genre, but the majority of them will contain clean interludes or lulls, usually as parts of a build-up in themselves. Relevant examples include "False Light" from Oceanic by Isis, or "Australasia" from Australasia by Pelican.

Criticism:

Since this genre is relatively new and is only represented by a small number of artists, the need for an entirely independent classification of music has occasionally been questioned by music reviewers and listeners. As a label, some see "post-metal" as redundant, since some bands listed as post-metal contain many elements similar to doom metal, progressive metal, sludge metal, and stoner metal. Others, however, argue that these elements have been combined and altered in ways that go beyond the boundaries of those respective genres, creating the need for a single, distinguishing label.

Pelican's Trevor de Brauw said, "I have an affinity for metal, but I don't think of Pelican as a metal band. So when people call us 'instrumetal', or post-metal, or metalcore or whatever, I can see why they say that, but it's not something that I feel a close connection with… I feel our has more in common with punk and hardcore."

Aesthetic or visual similarities in album art and performance are cited as derivative in claims that post-metal is an overly incestuous movement for its relatively small group of bands and musicians. Isis is often cited as the source of this shared imagery, although bands with similar visual themes playing in the post-metal style existed before Isis greatly popularized the subgenre.