Bluegrass has roots in traditional English, Scottish, and Irish ballads and dance tunes, and in traditional African American blues and jazz. Bluegrass features acoustic stringed instruments and emphasizes the off-beat. Notes are anticipated, in contrast to laid-back blues where notes are behind the beat, which creates a higher energy characteristic.
In bluegrass, as in some forms of jazz, one or more instruments each takes its turn playing the melody and improvising around it, while the others perform accompaniment, especially in tunes called breakdowns. This is in contrast to old-time music, in which all instruments 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. 1940s– .
Just saw Ricky Skaggs here in Athens! https://www.youtube.com/watch?v=TfDY3EdCl2U