A type of music from the Bluegrass states of America in the Appalachian region which became prominent in the 1940s. In origin, it owes much to the Irish Scots and English settlers. It is mainly acoustic and uses a line up of Guitar, Double Bass, Mandolin, Fiddle and 5-string Resonator Guitar or Dobro.
Arguments abound regarding the status of Bluegrass - Folk or Roots? Folk, by definition is part of an oral tradition amongst ordinary people. Bluegrass is an invented genre and has had professional music artists from the outset.
The best known Bluegrass tune is probably the theme from the film Deliverance (Duelling Banjos), which is the bane of every banjo players life. Other notable Bluegrass tunes are Foggy Mountain Breakdown, Ballad of Jed Clampett and Orange Blossom Special.
There is an organisation for Bluegrassers - The International Bluegrass Music Association out of Nashville (where else).