Bluegrass music is an outgrowth of Southern Appalachian folk music. Bill Monroe is the father of this genre which is characterized by "high lonesome" vocals and string instruments.
Bluegrass music started way back in the 1940s during the world war. Most experts agree that the founding father of Bluegrass music is Bill Monroe. The term "Bluegrass" originated from Bill's band, "Blue Grass Boys".
Bluegrass was "invented" by Bill Monroe when he called his band Bill Monroe and the Bluegrass Boys. Kentucky, where they were from, is the Bluegrass state.