Verse–chorus form is a musical form common in popular music, used in blues and rock and roll since the 1950s, and predominant in rock music since the 1960s. In contrast to thirty-two-bar form, which is focused on the verse (contrasted and prepared by the B section), in verse–chorus form the chorus is highlighted (prepared and contrasted with the verse). "Many popular songs, particularly from early in [the 20th] century, are in a verse and a chorus (refrain) form. Most popular songs from the middle of the [20th] century consist only of a chorus."