After completing this lesson, you will be able to

  1. Define form, especially in the musical sense
  2. Differentiate between repetition, contrast, and variation in musical form
  3. Summarize two methods of naming musical form

Musical Form refers to the arrangement of various components in a piece of music. It is a way of seeing the "big picture" in a musical composition. Think of musical form as a house to be explored: you walk through the front door and explore several different rooms, all different in size, shape, and purpose, before exiting via the back door. In the musical sense, the front door represents the introductory material, the rooms represent various sections of the composition, and the back door acts as the closing material. Understanding the structure of a piece of music can add a great deal of comprehension and appreciation.

Repetition vs. Contrast; Variation

Repetition and contrast are essential ingredients in a successful piece of music. Repetition provides a sense of stability, giving the listener a pleasurable feeling when something previously heard is repeated. The refrain (or chorus) of a popular song serves this function by utilizing the same words and music with each reiteration. If a piece of music contains only constant change, our brain may become weary at trying to sort it all out and simply stop listening.

Contrast provides the crucial function of variety. If a piece of music uses only one musical idea, repeated over and over, we may become bored and uninterested, unwilling to continue listening. Contrast can supply a change of emotion, conflict, and a sense of momentum-wondering what will come next.

One compositional technique, variation, combines repetition and contrast simultaneously. In a variation, a musical idea is repeated over and over, with a slight amount of change taking place each time. Over the length of a piece of music, variation may nearly completely transform a musical idea until very little of its original state remains. However, the change takes place so gradually we may barely notice the overall metamorphosis that has taken place.

How To Describe Form

There are various ways of describing the repetition, change, and variation that occurs in a musical composition. One can simply name each section using a word, or, as musicians normally do, use different letters to denote the same. Using the average popular song as an example, we can see how this works both ways.

Average Popular Song




First Verse

First words and music


Refrain (Chorus)

New words and music


Second Verse

Sound like first verse, but with some changes (like new words!)



Same as first refrain



New material; usually instrumental solo


Third Verse

Sounds like first verse, etc.



Same as first refrain



Similar to previous refrains, but with modest changes (improvised vocal, fade, etc.)


Using the letter method, we can describe this song as having the form A B A' B C B B'. The small marks to the upper right of one A and one B designate variation. Variation in the second verse is created by the use of new lyrics, while the final refrain may use some vocal improvisation, instrumental improvisation, fadeout, etc. to keep it from sounding the same. If a third verse with new lyrics had appeared we could have labeled it A''.

One rock/pop music group used the form of a song as the title. Genesis titled the opening track on their 1981 album ABACAB after the song's formal design.

The letter method is also used for instrumental music, where terms such as verse and refrain aren't suitable.

Naming Forms

Some forms are so common they have been given names as a type of shorthand. These are used mostly to designate instrumental music from the early 1600s to the present. Here is a list of some common forms and their descriptions:

Common Forms




AB (each may be repeated: AABB)





Theme & Variations

AA'A''A'''A'''' etc.

There are few forms, such as Ritornello and Sonata-allegro that cannot be easily described using letters. For these we will use names for the various sections.

A Final Word

Form is a nice, tidy way of describing the large-scale structure of a musical work. However, a particular form is not a rule that composers must adhere to. Rather, they serve as general structures for composers to work from. One must listen very closely and use musical memory to detect repeating and contrasting sections.