The 32-bar form, also known as the AABA song form, American popular song form and the ballad form, is a song structure commonly found in Tin Pan Alley songs and other American popular music, especially in the first half of the 20th century.
As its alternative name AABA implies, this song form consists of four sections: an eight-bar A section; a second eight-bar A section (which may have slight changes from the first A section); an eight-bar B section, often with contrasting harmony or "feel"; and a final eight-bar A section. The core melody line is generally retained in each A section, although variations may be added, particularly for the last A section.
Examples of 32-bar AABA form songs include "Over the Rainbow", "What'll I Do", "Make You Feel My Love", "Blue Skies",. Many show tunes that have become jazz standards are 32-bar song forms.