A refrain (from Vulgar Latin refringere, "to repeat", and later from Old French refraindre) is the line or lines that are repeated in music or in poetry — the "chorus" of a song. Poetic fixed forms that feature refrains include the villanelle, the virelay, and the sestina. In popular music, the refrain or chorus may contrast with the verse melodically, rhythmically, and harmonically; it may assume a higher level of dynamics and activity, often with added instrumentation. Chorus form, or strophic form, is a sectional and/or additive way of structuring a piece of music based on the repetition of one formal section or block played repeatedly. Usage in history In music, a refrain has two parts: the lyrics of the song, and the melody. Sometimes refrains vary their words slightly when repeated; recognizability is given to the refrain by the fact that it is always sung to the same tune, and the rhymes, if present, are preserved despite the variations of the words. Such a refrain is featured in "The Star-Spangled Banner," which contains a refrain which is introduced by a different phrase in each verse, but which always ends: O'er the land of the free, and the home of the brave. A similar refrain is found in the "Battle Hymn of the Republic," which affirms in successive verses that "Our God," or "His Truth," is "marching on." Refrains usually, but not always, come at the end of the verse. Some songs, especially ballads, incorporate refrains (or burdens) into each verse. For example, one version of the traditional ballad "The Cruel Sister" includes a refrain mid-verse: There lived a lady by the North Sea shore, Lay the bent to the bonny broom Two daughters were the babes she bore. Fa la la la la la la la la. As one grew bright as is the sun, Lay the bent to the bonny broom So coal black grew the other one. Fa la la la la la la la. . . . (Note: the refrain of 'Lay the Bent to the Bonny Broom' is not traditionally associated with the ballad of "The Cruel Sister" (Child #10). This was the work of 'pop-folk' group Pentangle on their 1970 LP Cruel Sister which has subsequently been picked up by many folk singers as being traditional. Both the melody and the refrain come from the ballad known as "Riddles Wisely Expounded" (Child #1).) Here,