Rock n' roll
A type of American popular music of the 1950's. In 1955 Bill Haley and His Comets' hit recording "Rock Around the Clock" became the best selling record thus establishing Rock n' Roll as the dominant popular style. Essentially Rock n' Roll is a highly rhythmic style of blues and most compositions are in some form of the 12-bar blues form. The electric and amplified instruments ( guitar, sax, drum kit, piano, and bass) allowed the performers to emphasize the first beat. Rock n' Roll became the blanket term for popular music in the late 1950's.