Binary forms contain two reprises.

Binary forms can either be simple or rounded.

Simple and rounded binary forms may both feature a balanced aspect.

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In the context of musical form, the term "binary" refers to a formal type that has two main parts. These parts are often called reprises because each is typically repeated. Binary forms are common in 17th-, 18th-, and 19th-century repertoire, and they were used heavily in dance music.

There are two types of binary form: rounded and simple. Both forms have the possibility of featuring a balanced aspect as well (note: balanced binary is often described as its own type of binary form, but that approach is not taken here).

Binary form is typically one of the shorter forms, and because of that, it is often embedded within larger, compound forms like compound ternary form.

Repeat Structure and Types of Binary Form

[](https://viva.pressbooks.pub/app/uploads/sites/12/2020/04/reprises-diagram.png)

Example 1. Abstract diagram of the repeat structure in binary form.

In 17th- and 18th-century classical music, each reprise of the binary form is typically repeated, as in Example 1. The listener will hear the following structure:

Reprise 1

Reprise 1

Reprise 2

Reprise 2

In 17th- and 18th-century music, it is very common to find the repeat signs written in the score. Decorative improvisation on the repeat was expected without being specified in the score. But in the 19th century, it became more common for composers to write out the repeat instead of using repeat signs. This may be done to indicate specific decorations on the repeat, to include changes in some musical domain (like instrumentation or register), and/or to expand the music beyond the length of its first statement.

While having two—usually repeated—reprises is common to all binary forms, there are two relatively distinct sub-types that capture the form's larger melodic organization: rounded and simple, shown in Example 2. Formal organization is represented with uppercase letters and prime symbols.

The first section of a binary form piece is represented with the letter A. In both subtypes of binary form, A is the main section and presents the main melodic material (see Formal Sections in General).

B sections (the contrasting sections) vary depending on the type of binary form (Example 2). Both forms can also feature a balanced aspect (represented with an x in parentheses), as discussed further below.

[](https://viva.pressbooks.pub/app/uploads/sites/12/2020/04/binary-form-diagrams-overview.png)

Example 2. Abstract diagram of each binary form.

Rounded Binary Form

[](https://viva.pressbooks.pub/app/uploads/sites/12/2020/04/rounded-binary-diagram.png)

Example 3. Abstract diagram of rounded binary form.

In rounded binary, the beginning of A returns in the home key somewhere in the middle of the second reprise. It is not necessary for all of A to return (though often it does)—only the beginning. While the returning material may be exactly the same, it's also common to see slight variations, like change of octave, accompanimental pattern, and/or melodic embellishments. If there is variation, you should still be able to experience the feeling of return when the A material comes back. If unsure, you can expect the harmonic analysis to remain essentially the same, the chord changes will likely be in the same metric locations, and the scale degrees of the melody will also be in the same order and in the same metric locations; just make sure to account for the possibility of slight variation in the domains listed above.

In rounded binary form, the second reprise starts with a B section. Typically, the B section is less stable than the A section and may involve common destabilizing features like sequences, chromaticism, and dominant pedals. In some binary forms, however, the B section is quite stable but simply presents different thematic material than A (see, for example, the B section of the Trio from the third movement of Mozart's String Quartet in G major, K. 80).

Rounded Binary Example

The Menuetto from the third movement of Mozart's Symphony no. 25 in G minor (Example 4) is a clear instance of a rounded binary form typical of the mid- to late 18th century. After a relatively stable thematic statement during the first reprise (mm. 1–12, A), the second reprise (mm. 13–36) can easily be divided into two distinct parts, B (mm. 13–20) and A′ (mm. 21–36). The impression of a division is the result of the return of A material at m. 21 and the half cadence that precedes it at m. 20.

In the 18th century, half cadences before the return of A in rounded binary forms are quite common. In the 19th century, however, composers may also elide or otherwise obscure this boundary, as Chopin does between mm. 16 and 17 in the rounded binary form found in mm. 1–24 of his polonaise in A major, Op. 40, no. 1.

[](https://viva.pressbooks.pub/app/uploads/sites/12/2019/06/Mozart_Symphony_No_25_3rd_Minuetto_Only.jpg)

Example 4. Mozart, Symphony no. 25 in G minor, 3rd movement, Menuetto.

Simple Binary Form

In simple binary, there is no substantial return of opening material in the second reprise. Instead, the material in the second reprise takes one of two possible manifestations:

A′ (note the prime symbol): The second reprise, though not a repeat of the first reprise, continues with the same sorts of ideas. As the A material is always present, there is no “return” to the opening material.

B: The second reprise contains relatively new material throughout.

[](https://viva.pressbooks.pub/app/uploads/sites/12/2020/04/simple-binary-a-b.png)

or

[](https://viva.pressbooks.pub/app/uploads/sites/12/2020/04/simple-binary-a-a.png)

Example 5. Abstract diagrams of simple binary form.

Simple Binary Example

The Bourrée from Bach's Lute Suite i