Sectional Form - Classical / Fixed

Binary / Rounded Binary

Two different main sections (A B). Commonly in Western classical music, the A section will move away from the tonic, with a strong cadence in another key, and the B section will move back and end strongly in the tonic.

Pieces in binary form have two parts: A and B.

Sections A and B can be more contrasting than in binary form.

Rondo

One section returns repeatedly, with a section of new music before each return. (A B A C A ; sometimes A B A C A B A)

In the rondo form, section A is repeated several times with new sections presented between each repetition. Follows the basic form:

We can add more sections as in the following example:

Section A can be repeated with variations. Composers generally try to achieve some contrast between section and the use of differet keys for different sections is very common.

Strophic

Composed of verses. The music is repeated sections with fairly small changes. May or may not include a refrain.

The opposite of strophic form, with new music written for every stanza, is called through-composed.

Strophic Form Examples:

Arch Form

The most popular arch-form structure is ABCBA.

In music, arch form is a sectional structure for a piece of music based on repetition, in reverse order, of all or most musical sections such that the overall form is symmetric, most often around a central movement. The sections need not be repeated verbatim but must at least share thematic material.