Bluegrass Music originated from a mixture of Irish, Scottish and African-American Music which started in Appalachia.
Father of Bluegrass
The style of bluegrass was never invented by just one person. It has developed over the years in since the beginning of the 20th century. Bill Monroe is considered the father of bluegrass. Before him there was no name for this style of playing.
In the 60's as it was becoming more popular, people wanted a name to call this kind of music and since Bill Monroe was the oldest musician they asked him to name it. He was from Kentucky and his band's name was the "Blue Grass Boys" so they called the style "Bluegrass"!
The music of Bluegrass is based strongly on the roots of Irish and Scottish Music. Many Bluegrass tunes are similar to Irish and Scottish tunes, but just played in the Bluegrass style.
Old time music is also a very similar style of music. The Bluegrass style is played with harmony but with Irish, Scottish and Old Time the instruments only play lead or backup and only rarely play harmony.
A Bluegrass Band is traditionally composed of a Fiddle, Guitar, Mandolin, Banjo, and Double Bass. When the Fiddle isn't soloing it is frequently played a third or a fifth lower than the melody which makes a harmony that is characteristic of Bluegrass.
The Guitar is played in the flatpicking style and the Banjo is played using the three finger picking style. The Bass isusually always played pizzacato rather than bowed.
More instruments are sometimes played like the Harmonica, the Drums and the Electric Guitar which some people call "Newgrass".When bluegrass is sung it has a it's own special harmony. It is usually sung with a lead voice and then a tenor singing higher than the lead and a baritone singing lower than the lead. Bluegrass singers sing with a high and lonesome sound.
Bluegrass festivals are excellent places to to hear bluegrass music. Also Bluegrass concerts are fun to attend. Below is a video of a concert of the Boston Pops Orchestra playing with Ricky Skaggs. It's not often that you see an orchestra playing bluegrass. The piece is Uncle Pen which was written by Bill Monroe about his Uncle Pen!