Composers use structure to shape and give balance to their music. Like the other musical elements, certain musical structures were used in different musical periods. For example, binary form was mainly used in Baroque dances, and sonata form was used mainly in the Classical period.
When you are trying to identify the structure of a piece of music, you will often find at least one of the following features will help you identify the different sections of the music.
You might be able to find sections that are repeated and then be able to work out if there is a pattern.
You might see a double bar line (sometimes with a repeat) at the end of a section. This can help you identify the starts and ends of sections.
Conventionally, some structures modulate to specific keys at certain points in the music. There are likely to be clear cadences at the end of sections, mainly to indicate a change of key.
Depending on the period of the music, some sections have distinctive melodies.
Some music may change texture between sections, or create significant textures at the beginning or end of sections.
Repeated text, such as a refrain or a chorus, can be used to give a piece of music structure.
We often label different sections in music with letters, such as A, B or C. This makes it clear when a section is repeated. For example, ABA has three sections, where the second section A is the same as or very similar to the first section A.