Song structure or the musical forms of songs in popular music are typically sectional, repeating forms, such as strophic form and is generally a part of the songwriting process. Other common forms include thirty-two-bar form, verse-chorus form, and the twelve bar blues. Popular music songs are rarely composed using different music for each stanza of the lyrics (songs composed in this fashion are said to be "through-composed"). This form can be used in any structural difference in melodies. A common format is verse, pre-chorus, chorus, verse, pre-chorus, chorus, bridge (middle eight), verse, chorus.