Scholes suggested that European classical music had only six stand-alone forms: simple binary, simple ternary, compound binary, rondo, air with variations, and
fugue (although musicologist
Alfred Mann emphasized that the fugue is primarily a method of composition that has sometimes taken on certain structural conventions). Charles Keil classified forms and formal detail as "sectional, developmental, or variational."
Sectional form This form is built from a sequence of clear-cut units that may be referred to by letters but also often have generic names such as
introduction and
coda; exposition, development, and
recapitulation; verse, chorus or
refrain, and
bridge. Sectional forms include:
Strophic form Strophic form – also called verse-repeating form, chorus form, AAA song form, or one-part song form – is a song structure in which all verses or stanzas of the text are sung to the same music
Medley or "chain" form Medley,
potpourri or
chain form is the extreme opposite, that of "unrelieved variation": it is simply an indefinite sequence of self-contained sections (
ABCD...), sometimes with repeats (
AABBCCDD...).
Binary form The term "Binary Form" is used to describe a musical piece with two sections that are about equal in length. Binary Form can be written as
AB or
AABB. Using the example of
Greensleeves provided, the first system is almost identical to the second system. We call the first system
A and the second system
A′ (A prime) because of the slight difference in the last measure and a half. The next two systems (3rd and 4th) are almost identical as well, but a new musical idea entirely than the first two systems. We call the third system
B and the fourth system
B' (B prime) because of the slight difference in the last measure and a half. As a whole, this piece of music is in Binary Form:
AA′BB′. There are both simple and compound ternary forms. Da capo arias are usually in simple ternary form (i.e. "from the head"). A compound ternary form (or trio form) similarly involves an ABA pattern, but each section is itself either in binary (two sub-sections which may be repeated) or (simple)
ternary form.
Rondo form This form has a recurring theme alternating with different (usually contrasting) sections called "episodes". It may be asymmetrical (
ABACADAEA) or symmetrical (
ABACABA). A recurring section, especially the main theme, is sometimes more thoroughly varied, or else one episode may be a "development" of it. A similar arrangement is the
ritornello form of the Baroque
concerto grosso.
Arch form (
ABCBA) resembles a symmetrical rondo without intermediate repetitions of the main theme.
Variational form Variational forms are those in which variation is an important formative element.
Theme and Variations: a
theme, which in itself can be of any shorter form (binary, ternary, etc.), forms the only "section" and is repeated indefinitely (as in strophic form) but is varied each time (A,B,A,F,Z,A), so as to make a sort of sectional chain form. An important variant of this, much used in 17th-century British music and in the
Passacaglia and
Chaconne, was that of the
ground bass—a repeating bass theme or
basso ostinato over and around which the rest of the structure unfolds, often, but not always, spinning
polyphonic or
contrapuntal threads, or improvising
divisions and
descants. This is said by Scholes (1977) to be the form
par excellence of unaccompanied or accompanied solo instrumental music. The
Rondo is often found with sections varied (
AA1BA2CA3BA4) or (
ABA1CA2B1A).
Sonata-allegro form Sonata-allegro form (also
sonata form or
first movement form) is typically cast in a greater ternary form, having the nominal subdivisions of
exposition, development and
recapitulation. Usually, but not always, the "A" parts (
exposition and
recapitulation, respectively) may be subdivided into two or three
themes or theme groups which are taken asunder and recombined to form the "B" part (the
development)—thus, e.g. (AabB[dev. of a and/or b]A1ab1+coda). The sonata form is "the most important principle of musical form, or formal type from the classical period well into the twentieth century." It is usually used as the form of the first movement in multi-movement works. So, it is also called "first-movement form" or "sonata-allegro form" (because usually the most common first movements are in allegro tempo). Each section of sonata form movement has its own function: • It may have an
introduction at the beginning. • Following the introduction, the
exposition is the first required section. It lays out the thematic material in its basic version. There are usually two themes or theme groups in the exposition, and they are often in contrasting styles and keys and connected by a transition. In the end of the exposition, there is a closing theme which concludes the section. • The exposition is followed by the
development section in which the material in the exposition is developed. • After the development section, there is a returning section called
recapitulation where the thematic material returns in the tonic key. • At the end of the movement, there may be a
coda, after the recapitulation. == Forms used in Western popular music ==