AABA is the schematic label for the classic 32-bar song form. This type of song breaks down into two opening verses, each 8 bars long, an 8-bar bridge or middle eight, and a final verse of 8 bars.

 

Many songs of the AABA type don't adhere strictly to the 8-8-8-8 format. Sometimes the songwriter chooses to lengthen the AABA song form by adding another bridge and a last A section, so that the format becomes AABABA. The second bridge may either be lyrically the same or different than the first bridge; it may also be an instrumental part. The last A section may also be a repeat of an earlier verse or an entirely new verse that gives the song a sense of completion.

 

See also popular song forms.