Bluegrass is a style of American music that features acoustic stringed instruments playing together in tight, energetic harmony. A typical bluegrass band includes a banjo, fiddle, guitar, mandolin, and upright bass, all played without amplification or electric instruments.

The music originated in the 1940s in Kentucky and nearby Appalachian states, created by musician Bill Monroe and named after his band, the Blue Grass Boys. Bluegrass draws from older folk traditions, Scottish and Irish fiddle music, and African American blues. The banjo gives bluegrass its distinctive bright, rapid-fire sound, while singers often harmonize in high, clear voices.

What makes bluegrass special is the way musicians play: they take turns stepping forward to perform elaborate solos while the others provide rhythm and backing. Unlike a classical orchestra, where everyone follows a conductor, bluegrass players listen carefully to each other and respond in the moment, creating music that feels both planned and spontaneous.

The word bluegrass also refers to a type of grass common in Kentucky, which is actually green but can look bluish when its seed heads bloom in spring, helping give the state its nickname, the Bluegrass State.