Rock and roll is a style of popular music that originated from the U.S in the mid-1950s, and by mid-1960s it had developed to an international style known as rock music, though the latter continued to be, rock and roll or rock 'n' roll or rock & roll. The music is associated with performers like Little Richard, Chuck Berry, Buddy Holly and the early Beatles. Instrumentation and arrangements are simple: three or four instruments, and, mostly the same number of cords while horns and strings and back up singers can be added.