Doom metal is an extreme subgenre of heavy metal music that typically uses slower tempos, low-tuned guitars and a much "thicker" or "heavier" sound than other heavy metal genres. Both the music and the lyrics are intended to evoke a sense of despair, dread, and impending doom. The genre is strongly influenced by the early work of Black Sabbath, who formed a prototype for doom metal. During the first half of the 1980s, a number of bands such as Witchfinder General and Pagan Altar from England, American bands Pentagram, Saint Vitus, the Obsessed, Trouble, and Cirith Ungol, and Swedish band Candlemass defined doom metal as a distinct genre.
The electric guitar, bass guitar, and drum kit are the most common instruments used to play doom metal (although keyboards are sometimes used), but its structures are rooted in the same scales as in blues. Guitarists and bassists often down tune their instruments to very low notes and make use of large amounts of distortion, thus producing a very "thick" or "heavy" guitar tone, which is one of the defining characteristics of the genre. Along with the usual heavy metal compositional technique of guitars and bass playing the same riff in unison, this creates a loud and bass-heavy wall of sound. Another defining characteristic is the consistent focus on slow tempos, and minor tonality with much use of dissonance (especially in the form of the tritone), employing the usage of repetitive rhythms with little regard to harmonic progression and musical structure.
Traditional doom metal vocalists favor clean vocals, which are often performed with a sense of despair, desperation, or pain; imitating the high-tone wails of Ozzy Osbourne (Black Sabbath), Frank Ferrara (Bang), Bobby Liebling (Pentagram), and Zeeb Parkes (Witchfinder General). So-called "epic doom" vocalists often take it a step further, singing in an operatic style. Doom metal bands influenced by other extreme metal genres often use growled or screamed vocals, as is the case of death-doom, black-doom, and funeral doom.