3 Section 1.3: Form and Structure

Form and Structure

One of the most essential tools of music performers and theorists alike is the ability to identify formal structure in music construction. To truly be able to identify visually and aurally the different parts of form within a composition the theory student must be able to use the three major building blocks of melody, harmony, and rhythm. Basically, the rest of this text. Composers will use rhythm and melody like a marker to outline different sections of their music. This enables the performer to know when to stop or pause when musically accurate.

There is some good news. The first and easiest form structure we study is called BINARY and means exactly what the word implies, something in two parts. When we have a BINARY structure in music we refer to the first part as “A” and the second as “B”. Both are evenly structured and have the same musical weight for symmetry which is important for the listener’s sense of closure in the short term and the long term.

Study the following example. Demonstrated is a short melody divided into two parts. The brackets designate two evenly spaced musical sentences or phrases. Focus on how the two lines look graphically in reference to each other. Even without rhythmic or notational reference one can compare the motion and amount of notes to discover the basic symmetry between two parts of the entire structure.



Two staves showing a binary form.

When the composer wishes to extend the melody, or has more to say within the music, they can add a third section to expand the composition. We call this format TERNARY for there are three distinct sections. Some composers will add new melodic material in this section similar to the A section or in some instances a direct repeat of the A section. The following example displays the format of ternary form with three distinct sections marked by the double bar line at the end of each staff.



Three staves showing a ternary form.



Binary and Ternary forms should be easy to figure out even for new students to music theory. However, once we pass these two forms, we enter into a new area of formal structure that takes patience and time to be able to identify. There are literally dozens of forms used by composers throughout music history. This section will cover the most commonly used forms in Popular, Jazz, and Classical music. So, we begin with song structure. Don’t forget we denote different sections with letters A,B, C… and so forth. However, we can also use other terms to define different sections of a song. These terms are VERSE, CHORUS, and BRIDGE. The verse is the literal bones of the song where the storytelling actually takes place. A chorus is a section that repeats at musically appropriate intervals that can sometimes include the title of the song or an important phrase that ties the verses together. The bridge is a tool composers use to give a song a texture or tonality change. We will use V to denote verse, C chorus, and B for bridge to outline some possible combinations.

One of the most common song formations is the strict rotation of verse and chorus with a bridge that transitions back to the chorus:


V1 – C – V2 – C – V3 – B – C – V4


Another common use of song form is to have two verses followed by a chorus with a bridge that transitions back to the verse:


V1 – V2 – C – V3 – V4 – C – B – V5 – C


If the story is long then we can use this formula of sorts to outline a longer format that is broken up by a bridge for musical balance:


V1 – V2 – V3 – V4 – C – B – V5 – V6 – V7 – V8 – C


The composer can also be concise and repetitive if that is what the story requires:


V1 – C – B – V2 – C – B – C – C


Many popular composers like to begin their work with the chorus, or HOOK this way they can end with it and have a bookend shaped format that gives the listener a sense of balance:


C- V1 – V2 – C – V3 – V4 – C


When the composer wishes to have every section be slightly different with no repetitive sections, we use the verse:


V1 – V2 – V3 – V4 – V5 – V6


This song format is hardly used unless there is a unique musical circumstance for example a musical or play that is not bound by pre-existing song formats.



Sonata Allegro Form was born in the Classical period of music history and the main format used by musicians of that period in music history. Many students may find this form difficult to deal with at first but once they have spent enough time studying scores and sheet music they will be able to see the form of the song without hearing it. The sonata allegro form comprises three main parts: EXPOSITION, DEVELOPMENT, and RECAPITULATION with two optional parts the INTRODUCTION and the CODA.

The exposition will contain two principal parts that define it in which there is a main theme or melody in the home or tonic key with a second theme in a contrasting key.



Exposition for Sonata Allegro Format.

An introduction in sonata allegro form is slower in tempo than the exposition statement and has a slightly different texture. This section is optional and classical composers used this option to balance the entire movement of a piece.

Introduction for Sonata Allegro Format.

As this form is used and developed composers began to find ways to elongate it with minor changes at the end of phrases usually referred to as “connective material” that prepares the listener for the next section.


The development section is a magical tool within the form that allows the composer to open up the tonal constraints of diatonic harmony (defined in Section II) and use both themes from the exposition for compositional substance. In many cases, the development is an elongated portion of the work and will sound completely different from the exposition with fragments of both themes and multiple modulations. The idea is that a musical idea is stated and then exposed in many variants that present the listener with new material that is derived from the one simple musical statement.


Recapitulation for Sonata Allegro Format.

The recapitulation is the restatement of both themes from the exposition, creating a sense of balance within the form and a place of rest for the entire piece. This is achieved by restating not only the first theme in the tonic key but also the second theme in the tonic key, not a contrasting key. This is designed to give the listener a sense of finality and closure for the entire work.


CODAS are small sections of music that appear at the end of musical works. It is also optional and can be used to balance out the entire form. Composers will use this to balance out the end of the composition to counter the optional introduction at the beginning of the work.

Codas for Sonata Allegro Format.



Jazz formats are tricky. Jazz composers rarely follow anyone’s rules but their own so there are many forms that are in use and have been in use for a number of years. Jazz musicians use a combination of binary, ternary, and song formats to depict the form of their compositions. We use the letter system again when communicating these formats to one another. The A section is always the verse, the B section is usually a chorus of some type and the C section is used as the bridge. In Jazz, improvisation is key and we can outline solo areas using the same terminology.

In many instances Jazz composers will start simple with a simple ternary structure:


A – A – B

A – B – B

A – B – C

Then there is the use of deliberate repetition:


A – B – A – B


The more diverse the composition the longer it can be:


A – B – C – A – B – C


Another popular formula is to use the sections in a palindrome:


A – B – C – B – A


Blues Form:

Blues comes in two traditional forms; 12-bar and 16-bar. For the purposes of our study, we will focus on the 12-bar blues because it is more common in use. When dissecting the 12-bar Blues we look at it in three equal parts each four measures in length. Further, when mapping out the form we use the tonal areas within those sections as transferable labels that create a type of shorthand. The first example is a traditional 12-bar format grouped by chord. Once the student has completed or referred to the Harmony section of this text, the Blues formats will become more accessible. For now, realize that there are only three chords used in the traditional format Tonic or I, Sub Dominant or IV and the Dominant or V. These markings can be as utilitarian as the formal markings from a previous form, i.e A-B-C or I-IV-V.


Traditional Blues Progression:

A traditional blues progression.

The traditional Blues format made its way into popular music via Country and Rock and Roll. Early forms of both types of music are rooted in the harmonic, melodic and rhythmic practices of traditional Blues. Much of popular music is the extension or evolution of these early foundations so it is important to understand the form and eventually the harmonic practice of the Blues format.

Country and Rock would not be the only genres of music to grab on to the Blues form. Jazz musicians play blues tunes all the time and we tend to alter chords during performance. Chord substitution is a regular practice in Jazz, it allows the player a broader palette of sounds from which to choose during improvisation. There are rules to chord substitution, one can’t switch out anything anywhere, there must be a method.

The following example is what is possible for chord substitutions over a traditional Blues using only the three chords originally supplied. Moving the tonality of the progression from chord to chord quicker changes the feel of the song. Both forms are acceptable during performance. Performers will determine which chord to substitute and when based on musical judgements either predetermined or in the moment when another musician’s performance demands it.


Blues progression with Chord Substitution:

A blues progression with chord substitution.

Jazz performers will also dip into the classical area for chord substitutions and make use of older rules but set them in modern work. For instance, the use of artful chromaticism. CHROMATICISM is the use of tones or chords outside the perceived tonal area of a song. These substitutions have the ability to fill out a Blues progression and make it blossom with tonal color. Musicians will use the word color to refer to a specific sound, performance technique, or even mood of a song. The Blues by definition is all of those things at once and more so color as a descriptive form of a musical event is quite common.

If one overextends and attempts substitutions in appropriate places of the form, then the original intent of the song is lost and the listener has no frame of reference. So, have fun but beware.

Blues Progression with chord substitution rooted in chromatic movement:

A blues progression with chord substitution rooted in chromatic movement.

Jazz Blues progression with chromatic chord substitutions:

A Jazz Blues progression with chromatic chord substitutions.



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A Practical Approach To Understanding Music Theory Copyright © 2022 by Charles B. Brooks is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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