Bluegrass is a genre of American roots music that developed in the 1940s in the Southern United States. It is characterized by its distinctive instrumentation which typically includes the banjo, guitar, fiddle, mandolin, and upright bass. The genre was popularized by Bill Monroe and his band 'The Blue Grass Boys', with the name 'Bluegrass' being derived from the band's name. Bluegrass has a strong tradition of improvisation and complex, high-speed picking, with a significant influence from the musical traditions of Appalachia.