Multiple guitar players
||This article possibly contains original research. (March 2008)|
Multiple guitar players, electric and/or acoustic, in rock and other related genres, sometimes perform different musical parts, such as instrumental melodies, "licks", riffs, guitar solos, and chords.
The band can divide up the roles by assigning one or more performers the role of lead guitar and assigning another guitarist (or several guitarists) the role of rhythm guitar. Alternatively, two or more guitarists can share the lead and rhythm roles throughout the show, or both guitarists can play the same role ("dual lead guitars" or "dual rhythm guitars").
There are several ways that multiple guitar players are used. In the standard configuration used in many rock, hard rock, and metal bands, a lead guitar player performs melody lines and guitar solos and one (or sometimes more) rhythm guitar player(s) plays chords or riffs as an accompaniment. The rhythm guitar part outlines the chord progression of a song and provides a rhythmic pulse. The Beatles-style quartet consisting of two electric guitars, an electric bass, and drums has become the standard formation for rock groups.
Dual lead guitars
In many heavy metal subgenres and occasionally in other genres, bands may use two lead guitarists. Some bands use the two lead guitars to play two independent melody lines, which creates interweaving counterpoint, while other bands use one lead guitarist to perform instrumental melodies while the second lead guitarist adds lead embellishments and improvised flourishes. In some bands, the two guitarists may play previously composed lead lines or riffs in harmony, usually in diatonic thirds or sixths. This practice has been extended to the point where some guitarists compose solos before performing them (as opposed to improvising), which allows the entire solo to be harmonized in this manner.
In Russell Hall's article 10 Great Dual Lead Guitar Albums, he discusses albums with "spectacular dual lead guitar work", including Derek and the Dominos' Layla and Other Assorted Love Songs (1970), which paired Eric Clapton and Duane Allman; Wishbone Ash's Argus (1973) and Thin Lizzy's Jailbreak (1976), which were an early use of "dual-guitar harmonies"; Lynyrd Skynyrd's Second Helping (1974), which had "three guitars parlaying swampy Southern blues"; and the Allman Brothers' At Fillmore East (1971), in which "Duane Allman teamed with Dickey Betts to craft tangled solos that combined blues rapture with the improvisational ethos of jazz." He also praises proto-punk or punk-influenced albums, such as Lou Reed's Rock 'n' Roll Animal (1974), which is "powered by a dual lead guitar tapestry crafted by Dick Wagner and Steve Hunter"; Television's Marquee Moon (1977), which used a "jaggedly brilliant twin-guitar approach" of Tom Verlaine and Richard Lloyd; and Sonic Youth's Daydream Nation (1988), in which the two guitarists blended "ringing harmonics, molten distortion, and alternate tunings". Iron Maiden's, The Number of the Beast, was propelled by Bruce Dickinson’s operatic vocals and the dynamic, blistering two-guitar swirl of Dave Murray and Adrian Smith. 
Alternatively, each guitarist may play both lead and rhythm guitar parts at different parts of a song or at different parts of a performance. Many songs also feature two guitarists playing riffs or chord progressions in unison. They will often trade off guitar solos; usually, when one guitarist is performing a solo, the other will maintain a backing rhythm by playing chords. In some songs, both guitarists may solo at the same time. Some examples from rock and heavy metal include Judas Priest, Slayer, Iron Maiden, Thin Lizzy, Wishbone Ash, and The Eagles. Some bands record their guitars on separate channels, so it will sound as if one guitar will play a solo on the right side, then the other guitar will come in and take over on the left side, or vice-versa.
Dual rhythm guitars
Another approach is to use two guitarists to play rhythm guitar, which is known as "dual rhythm guitar". Belgian Gypsy jazz guitarist Django Reinhardt (1910–1953) performed during the swing era with a band which "consisted of violin, lead guitar, two rhythm guitars, and standup bass",. Reinhardt's use of two acoustic rhythm guitars helped to create a strong rhythmic pulse for the group, which did not have a drummer. Gypsy jazz guitarists use a special strumming technique called La Pompe.
The Rolling Stones in their first incarnation frequently featured interlocking rhythm guitars, played by Keith Richards and Brian Jones, in which each musician would play a different rhythm guitar part. Both guitarists would play solos on their recordings, though Jones would do it particularly if slide guitar was wanted; Jones also played the harmonica and several other instruments in the studio.
Heavy metal pioneers Judas Priest popularized the dual rhythm guitar approach in a metal context. A number of Judas Priest songs use two guitarists playing the same rhythmic riff simultaneously, often on the same octave, which creates a more powerful sound.
Afropop big bands and mi-solo
Some styles of African popular music feature multiple lead and rhythm guitarists in "big band" line up. The famous Soukous band TPOK Jazz additionally featured the unique role of mi-solo, (meaning "half solo") guitarist, playing arpeggio patterns and filling a role "between" the guitar and rhythm guitars.
In rock or metal bands with a single guitarist, the guitar player usually plays rhythm guitar for most of each song, to accompany the vocalist. However, the guitarist may also perform solos during a song. In a small ensemble, such as a power trio (electric guitar, electric bass, and drums) e.g. Rush, Nirvana, and Cream, the loss of the rhythm guitar's accompaniment role during a lead guitar solo can considerably thin out the sound of the band. To resolve this problem for recordings, some bands with a single guitarist use overdubbing on recordings to record a rhythm guitar part behind their guitar solos, or more notably in the case of Rush, whereupon during the guitar solo, the bassist Geddy Lee played rhythm on a double neck while playing bass notes with his feet on Moog Taurus pedals.
In live performances, bands with a single guitarist can create the effect of having rhythm guitarist playing behind the guitar solos by using digital looping pedals. Looping effect pedals can be used to record a short riff or chordal accompaniment, which the guitarist can then solo over. In some cases, a session musician may play a rhythm guitar part offstage during the lead guitar solo, or a touring guitarist can be hired.
Several bands such as Radiohead, Switchfoot, Alesana, Oceansize, Relient K, Periphery, Skálmöld, the Chinese Democracy line-up of Guns N' Roses, Collective Soul, Lynyrd Skynyrd, Foo Fighters, Earshot, Pearl Jam (on certain songs), and the newest incarnation of Iron Maiden have three guitarists. The G3 tour, devised by Joe Satriani and Steve Vai, also features three guitarists. The deathcore bands Whitechapel and Chelsea Grin also feature three guitarists, resulting in a very powerful live sound.
Bands with a member playing a keyboard instrument sometimes assign this instrumentalist a role analogous to an additional guitarist, so that the keyboardist not only provides accompaniment and a fuller sound, but also plays solos. Even bands with only a single guitarist can achieve effects similar to a band with multiple guitarists in this way, although some bands with multiple guitarists also employ keyboard players. By using guitar-like playing techniques, sounds, guitar amps or even a keytar the keyboardist can emulate the role of a guitarist to a very high degree. Emerson, Lake & Palmer were known for not having a regular guitar player at all, but Keith Emerson's aggressive "shredding" style helped to retain a hard rocking band sound nevertheless.