In music, accompaniment is the art of playing along with a soloist or ensemble, often known as the lead, in a supporting manner as well as the music thus played. An accompaniment figure is a gesture used repeatedly in an accompaniment, such as:
Harmonic accompaniment is music played to accompany a melody line; it is usually chordal and played by such instruments as (acoustic or electric) guitar, piano, organ and bass guitar, but it can also be played by instruments that ordinarily play the melody, such as the violin. In most tonal music the melody and accompaniment are written from and share the same group of pitches, while in much atonal music the melody and accompaniment are chosen from entirely separate groups of pitches, often from different hexachords. See also: chord-based.
An accompanist is one who plays an accompaniment. A number of classical pianists have become famous as accompanists rather than soloists; the best known example is probably Gerald Moore, well known as a Lieder accompanist. In some American schools, the title collaborative pianist (or collaborative artist) is replacing the title accompanist.
Dialogue accompaniment is a form of call and response in which the lead and accompaniment alternate, the accompaniment playing during the rests of the lead and providing a drone or silence during the main melody or vocal. (van der Merwe 1989, p.320)
The term accompanist is also used to refer to a musician (generally pianist) who will not necessarily be participating in the performance of a piece of drama that utilizes music (musical theater, opera, etc.) but is used during an audition or rehearsal in lieu of the actual musician(s).