Rock

Rock music is a genre of popular music that originated as "rock and roll" in the United States in the 1950s, and developed into a range of different styles in the 1960s and later, particularly in the United Kingdom and the United States. ... Musically, rock has centered on the electric guitar, usually as part of a rock group with electric bass guitar and drums. Typically, rock is song-based music usually with a 4/4 time signature using a verse-chorus form, but the genre has become extremely diverse. Like pop music, lyrics often stress romantic love but also address a wide variety of other themes that are frequently social or political in emphasis. Rock places a higher degree of emphasis on musicianship, live performance, and an ideology of authenticity than pop music. [Rock music. Wikipedia]