Bluegrass music is a genre of American roots music that developed in the 1940s in the Appalachian region of the United States. The genre derives its name from the band Bill Monroe and the Blue Grass Boys. Bluegrass has roots in African American genres like blues and jazz and North European genres, such as Irish ballads and dance tunes. Unlike country, it is traditionally played exclusively on acoustic instruments such as the fiddle, mandolin, banjo, guitar and upright bass. It was further developed by musicians who played with Monroe, including 5-string banjo player Earl Scruggs and guitarist Lester Flatt. Bill Monroe once described bluegrass music as, "It's a part of Methodist, Holiness and Baptist traditions. It's blues and jazz, and it has a high lonesome sound."
Bluegrass features acoustic stringed instruments and emphasizes the off-beat. The off-beat can be "driven" (played close to the previous bass note) or "swung" (played farther from the previous bass note). Notes are anticipated, in contrast to laid-back blues where notes are behind the beat; this creates the higher energy characteristic of bluegrass. In bluegrass, as in most forms of jazz, one or more instrumentalists take a turn playing the melody and improvising around it, while the others perform accompaniment; this is especially typified in tunes called breakdowns. This is in contrast to old-time music, where all instrumentalists play the melody together, or one instrument carries the lead throughout while the others provide accompaniment. Breakdowns are often characterized by rapid tempos and unusual instrumental dexterity, and sometimes by complex chord changes.
