Song structure or the musical forms of songs in traditional music and popular music are typically sectional, repeating forms used in songs, such as strophic form and is a part of the songwriting process. Other common forms include thirty-two-bar form, verse-chorus form, and the twelve bar blues (the latter is used in blues and blues rock. 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", an approach used in classical music). Pop and traditional forms can be used even with songs that have structural differences in melodies. A common format is intro, verse, pre-chorus, chorus, verse, pre-chorus, chorus, bridge ("middle eight"), verse, chorus and outro.