In music, we use the word “form” to describe how a song is organized. Form refers to the structure of a song, from its smallest building blocks of notes and rhythms to its organizing principles of phrases and themes.
A phrase is a short series of notes – usually a few measures long – that sounds more or less complete, even if you listen to it outside the context of the whole song. Think of a phrase as a sentence in a chapter of a book – it’s just a small piece of the story, but it can stand on its own.
A theme is a melody that is constructed of several phrases put together. Think of a theme as a paragraph – it has a beginning, middle, and end.
Some simple songs have only one theme, but many songs have multiple themes. All of these themes together make up a complete and interesting musical picture.
Here are some of the more commonly-used forms in western music:
Strophic
A strophic song features lots of repetition. It may feature several verses in which the melody remains the same but the lyrics change. It may also alternate between verses and choruses. Most of the music that you listen to is probably strophic. Popular genres like rock, hip hop, and country use strophic form because it is easy for the listener to follow along with the music, and perhaps even sing along.
Through-composed
A through-composed song has little to no repetition. Every phrase sounds different, and the song keeps evolving and moving forward until the end. This style was used more commonly during the Classical period. It’s not very popular today because most pop songs rely on repetition and predictability to “hook” a listener.
Rondo
A rondo alternates a repeated section with new musical material: ABACADA. This form was very popular in the Classical period. Mozart’s “Rondo Alla Turca” is a famous example of this style.
Sonata
The sonata form was especially popular in the Classical period, and it was used as an organizing principle for many types of music. The sonata form is divided into three sections:
- The exposition introduces the key themes of the song (typically the song would have two melodic themes.) The exposition will begin in one key, but with the second theme it will move to a new key.
- The development explores and plays with the two themes, playing them in fragments and moving through many different keys.
- The recapitulation brings a sense of resolution to the song. It brings us back to the original key and restates the two themes, bringing the song to a close.
