Rhythm guitar refers to the role of the guitar in playing accompaniment in various musical styles. Typically the role of the rhythm guitars is to combine a rhythmic accent with simple or complex harmonies, as the song demands. There are a great many specific styles of rhythm guitar: Big Band, as exemplified by Freddie Greene of the Count Basie Orchestra; Western Swing as played by Eldon Shamblin of the Bob Wills Orchestra, or rock and roll music, as exemplified by Keith Richards of the Rolling Stones, to name a few.
In Rock and Roll, the role of the rhythm guitarist is typically expected to play a simple sequence of chordss around which the song is constructed. Often this chordal accompaniment is simplified to a cluster of two of three notes, sometimes called a "riff", that is repeated. In Jazz or Swing styles, the rhythm guitarist is also expected to integrate a moving bass or counter-melody in his or her playing.
