The classical blues typically consists of 12 bars. This means that the musical structure of the blues is divided into 12 measures or sections, each lasting for a specific amount of time. The 12-bar blues structure is a fundamental part of the blues genre and has been used in countless blues songs throughout history. It is characterized by a repeating chord progression that follows a specific pattern, typically consisting of three chords: the tonic (I), the subdominant (IV), and the dominant (V) chords. The lyrics of blues songs often follow a specific form as well, with the first line repeated and the second and third lines rhyming with each other. The 12-bar blues has been used in a wide range of music genres, from rock and roll to jazz to country music, and it remains a cornerstone of modern popular music.