Roles and playing styles
Most metal bassists play by plucking the strings with their fingers or by picking with a plectrum, often known as a pick. Using a pick can enable bassists to play rapid repeated notes and fast basslines, although some bassists, such as Steve Harris and Steve DiGiorgio, play such basslines without the use of a plectrum. While the types of bass lines vary in different metal subgenres, the bassist usually fulfills a similar role: anchoring the harmonic framework with bass notes that emphasize the roots of the chords and, along with the drums and rhythm guitar, establishing the beat. The bass is also used a solo instrument in some metal styles. While four-string basses (tuned E, A, D, G from lowest string to highest string) are the most common, since the 1990s, some metal bassists have used five-string basses for added lower range—a low "B". Five string basses are used in nu metal, as well as death metal, progressive metal and other heavy metal subgenres, to complement the downtuned guitars use by the guitarists. The five string bass is not an essential part to these genres, as some bands in these genres use standard tuned guitars or downtuned four string basses. Some bassists, such as John Myung from the progressive metal band Dream Theater, utilize a six string bass, which usually adds an additional high "C" above the "G" string of a five string bass. Most metal bassists play with fretted instruments, which have metal frets on the fingerboard. However, there are a few bassists such as Steve DiGiorgio and Jeroen Paul Thesseling who use fretless basses.
Most of the time, metal bass players play basslines which consist of a single note played at a time; that is, without playing multiple notes at the same time to form chords, the way a rhythm guitarist would on an electric guitar. There are, however, a few metal bassists who play chords. Robert Trujillo of Metallica is known for playing "massive chords"  and "chord-based harmonics"  on the bass. Lemmy of Motörhead often played power chords in his bass lines. When asked about whether he had begun as a rhythm guitarist, he stated:
No, I play a lot of notes, but I also play a lot of chords. And I play a lot of open strings. I just don't play like a bass player. There are complaints about me from time to time. It's not like having a bass player; it's like having a deep guitarist.
While bass guitar solos are much less common in metal than guitar solos for electric guitar, some metal bassists do play solos. Bass guitar solos are structured and performed in a similar fashion as rock guitar solos, often with the musical accompaniment from the verse or chorus sections. Bass solos are performed using a range of different techniques, such as plucking or fingerpicking. A small number of metal bassists do two-handed tapping styles in which they use both hands to play notes on the fretboard by rapidly pressing and holding the string to the fret. Players noted for this soloing technique include Cliff Burton and shred guitar-style bassist Billy Sheehan. Led Zeppelin's "Good Times Bad Times", the first song on their first album, contains two brief bass solos, occurring after the song's first and third choruses. Queen's bassist, John Deacon, occasionally played bass solos, such as on the song "Liar". Metallica's 1983 debut Kill Em All includes the song "(Anesthesia) Pulling Teeth," consisting entirely of a bass solo played by Cliff Burton. Manowar's bassist Joey DeMaio uses special piccolo bass for his extremely fast bass solos like "Sting of the Bumblebee" and "William's Tale".
Heavy metal bass players such as Geezer Butler (Black Sabbath), Alex Webster (Cannibal Corpse), Cliff Burton (Metallica), and Les Claypool (Primus, Blind Illusion) have used chime-like harmonics and rapid plucking techniques in their bass solos. In both published Van Halen concert videos, Michael Anthony performs unique maneuvers and actions during his solos. When playing bass solos, rock and metal bassists sometimes use effects such as fuzz bass or a wah-wah pedal to produce a more pronounced sound. Notably, Cliff Burton of Metallica used both effects. Due to the lower range of the bass, bass guitar solos usually have a much lighter accompaniment than solos for other instruments. In some cases, the bass guitar solo is unaccompanied, or accompanied only by the drums.
There is much less formal training available in college and university for metal bass, the way there is for bass guitarists learning jazz and the mainstream commercial genres (rock, R&B, etc.). Many metal bass players learn by ear, by copying bass lines from records and CDs, and by playing in a number of bands, which may include cover bands and tribute bands. Metal bassists may be able to take lessons from expert metal players or teachers. They may also be able to adapt techniques from other genres to the metal genre. As well, there are a range of books, playing methods, and, since the 1990s and 2000s, instructional DVDs and YouTube videos on how to play metal bass.
Metal bassists play in groups ranging in size from the power trio (guitar, bass and drums, with one or more of the members singing) to larger bands with multiple guitarists, keyboards, a bassist, a drummer and a vocalist. Some metal bassists sing lead vocals while they play bass, a role that Lemmy Kilminster of Motörhead did, and which Tom Araya of Slayer and Grutle Kjellson of Enslaved continue to do. Some metal bassists sing backup vocals while they play bass. Some metal bassists are also bandleaders or songwriters for their bands examples being Steve Harris and Nikki Sixx. In a few cases, traditional metal group bass players have also played another instrument, such as Led Zeppelin's John Paul Jones, who played Hammond organ on some songs or the bassists from mainstream metal bands such as Styx and the Scorpions who use a pedal keyboard, which is played with the feet.
Professional metal bassists may have a bass technician who tunes their basses before and during a performance, sets up the speaker cabinets, amplifiers and effects units, and performs routine maintenance on the instruments and equipment (e.g., changing strings, replacing speakers, replacing amplifier tubes, etc.).