In music, form refers to the structure of a musical composition or performance. In his book, Worlds of Music, Jeff Todd Titon suggests that a number of organizational elements may determine the formal structure of a piece of music, such as "the arrangement of musical units of rhythm, melody, and/or harmony that show repetition or variation, the arrangement of the instruments (as in the order of solos in a jazz or bluegrass performance), or the way a symphonic piece is orchestrated", among other factors.

These organizational elements may be broken into smaller units called phrases, which express a musical idea but lack sufficient weight to stand alone. Musical form unfolds over time through the expansion and development of these ideas.

Compositions that do not follow a fixed structure and rely more on improvisation are considered free-form. A fantasia is an example of this.

Labeling procedures ​

To aid in the process of describing form, musicians have developed a simple system of labeling musical units with letters. In his textbook "Listening to Music", professor Craig Wright writes,

The first statement of a musical idea is designated A. Subsequent contrasting sections are labeled B, C, D, and so on. If the first or any other musical unit returns in varied form, then that variation is indicated by a superscript number-- A1 and B2, for example. Subdivisions of each large musical unit are shown by lowercase letters (a, b, and so on).

Some writers also use a prime label (such as B', pronounced "B prime", or B'', pronounced "B double prime") to denote sections that are closely related, but vary slightly.

Levels of organization ​

The founding level of musical form can be divided into two parts:

• The arrangement of the pulse into unaccented and accented beats, the cells of a measure that, when harmonized, may give rise to a motif or figure.
• The further organization of such a measure, by repetition and variation, into a true musical phrase having a definite rhythm and duration that may be implied in melody and harmony, defined, for example, by a long final note and a breathing space. This "phrase" may be regarded as the fundamental unit of musical form: it may be broken down into measures of two or three beats, but its distinctive nature will then be lost. Even at this level, the importance of the principles of repetition and contrast, weak and strong, climax and repose, can be seen. Thus, form may be understood on three levels of organization. For the purpose of this exposition, these levels can be roughly designated as passage, piece, and cycle.

Passage ​

The smallest level of construction concerns the way musical phrases are organized into musical sentences and "paragraphs" such as the verse of a song. This may be compared to, and is often decided by, the verse form or meter of the words or the steps of a dance.

For example, the twelve bar blues is a specific verse form, while common meter is found in many hymns and ballads and, again, the Elizabethan galliard, like many dances, requires a certain rhythm, pace and length of melody to fit its repeating pattern of steps. Simpler styles of music may be more or less wholly defined at this level of form, which therefore does not differ greatly from the loose sense first mentioned and which may carry with it rhythmic, harmonic, timbral, occasional and melodic conventions.

Piece (or movement) ​

The next level concerns the entire structure of any single self-contained musical piece or movement. If the hymn, ballad, blues or dance alluded to above simply repeats the same musical material indefinitely then the piece is said to be in strophic form overall. If it repeats with distinct, sustained changes each time, for instance in setting, ornamentation or instrumentation, then the piece is a theme and variations. If two distinctly different themes are alternated indefinitely, as in a song alternating verse and chorus or in the alternating slow and fast sections of the Hungarian czardas, then this gives rise to a simple binary form. If the theme is played (perhaps twice), then a new theme is introduced, the piece then closing with a return to the first theme, we have a simple ternary form.

Great arguments and misunderstanding can be generated by such terms as 'ternary' and 'binary', as a complex piece may have elements of both at different organizational levels.[citation needed] A minuet, like any Baroque dance, generally had simple binary structure (AABB), however, this was frequently extended by the introduction of another minuet arranged for solo instruments (called the trio), after which the first was repeated again and the piece ended—this is a ternary form—ABA: the piece is binary on the lower compositional level but ternary on the higher. Organisational levels are not clearly and universally defined in western musicology, while words like "section" and "passage" are used at different levels by different scholars whose definitions, as Schlanker[full citation needed] points out, cannot keep pace with the myriad innovations and variations devised by musicians.

Cycle ​

The grandest level of organization may be referred to as "cyclical form".[citation needed] It concerns the arrangement of several self-contained pieces into a large-scale composition. For example, a set of songs with a related theme may be presented as a song-cycle, whereas a set of Baroque dances were presented as a suite. The opera and ballet may organize song and dance into even larger forms. The symphony, generally considered to be one piece, nevertheless divides into multiple movements (which can usually work as a self-contained piece if played alone). This level of musical form, though it again applies and gives rise to different genres, takes more account of the methods of musical organisation used. For example: a symphony, a concerto and a sonata differ in scale and aim, yet generally resemble one another in the manner of their organization. The individual pieces which make up the larger form may be called movements.

Common forms in Western music ​

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. Contrasting song forms include through-composed, with new music written for every stanza, and ternary form, with a contrasting central section.

The term is derived from the Greek word στροφή, strophē, meaning "turn". It is the simplest and most durable of musical forms, extending a piece of music by repetition of a single formal section. This may be analyzed as "A A A...". This additive method is the musical analogue of repeated stanzas in poetry or lyrics and, in fact, where the text repeats the same rhyme scheme from one stanza to the next, the song's structure also often uses either the same or very similar material from one stanza to the next.

A modified strophic form varies the pattern in some stanzas (A A' A"...) somewhat like a rudimentary theme and variations. Contrasting verse-chorus form is a binary form that alternates between two sections of music (ABAB), although this may also be interpreted as constituting a larger strophic verse-refrain form. While the terms 'refrain' and 'chorus' are often used interchangeably, 'refrain' may indicate a recurring line of identical melody and lyrics as a part of the verse (as in "Blowin' in the Wind": "...the answer my friend..."), while 'chorus' means an independent form section (as in "Yellow Submarine": "We all live in...").

Many folk and popular songs are strophic in form, including the twelve-bar blues, ballads, hymns and chants. Examples include "Barbara Allen", "Erie Canal", and "Michael, Row the Boat Ashore". Also "Oh! Susanna" (A = verse & chorus).

Many classical art songs are also composed in strophic form, from the 17th century French air de cour to 19th century German lieder and beyond. Haydn used the strophic variation form in many of his string quartets and a few of his symphonies, employed almost always in the slow second movement. Franz Schubert composed many important strophic lieder, including settings of both narrative poems and simpler, folk-like texts, such as his "Heidenröslein" and "Der Fischer". Several of the songs in his song cycle Die schöne Müllerin use strophic form.

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...).

Potpourri or Pot-Pourri (/ˌpoʊpʊˈriː/; French, literally "putrid pot") is a kind of musical form structured as ABCDEF..., the same as medley or, sometimes, fantasia. It is often used in light, easy-going and popular types of music.

This is a form of arrangement where the individual sections are simply juxtaposed with no strong connection or relationship. This type of form is organized by the principle of non-repetition. This is usually to be applied to a composition that consists of a string of favourite tunes, like a potpourri based on either some popular opera, operetta, or a collection of songs, dances, etc.

The term has been in use since the beginning of the 18th century, or to be more specific, since it was used by the French music publisher Christophe Ballard (1641–1715) for the edition of a collection of pieces in 1711. In the 18th century the term was used in France for collections of songs which, with a thematic link, were sometimes given stage presentation. Later the term was used also for instrumental collections, like the "Potpourry français", a collection of originally unconnected dance pieces issued by the publisher Bouïn.

Potpourris became especially popular in the 19th century. The opera overtures of French composers, such as François-Adrien Boïeldieu (1775–1834), Daniel Auber (1782–1871) and Ferdinand Hérold (1791–1833), or the Englishman Arthur Sullivan (1842–1900) belong to this type. Richard Strauss called the overture to his Die schweigsame Frau a "pot-pourri".

The "overtures" to light modern stage works (e.g. operettas or musicals) are almost always written in potpourri form, using airs from the work in question. There is usually some structure to the order presented though. The opening is usually a fanfare or majestic theme (presumably the supposed hoped-for most popular song number), followed by a romantic number, then a comical number; and finally a return to the opening theme or a variation thereof.

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'.

Binary form is a musical form in 2 related sections, both of which are usually repeated. Binary is also a structure used to choreograph dance. In music this is usually performed as A-A-B-B.

Binary form was popular during the Baroque period, often used to structure movements of keyboard sonatas. It was also used for short, one-movement works. Around the middle of the 18th century, the form largely fell from use as the principal design of entire movements as sonata form and organic development gained prominence. When it is found in later works, it usually takes the form of the theme in a set of variations, or the Minuet, Scherzo, or Trio sections of a "minuet and trio" or "scherzo and trio" movement in a sonata, symphony, etc. Many larger forms incorporate binary structures, and many more complicated forms (such as the 18th-century sonata form) share certain characteristics with binary form.

Structure ​

A typical example of a piece in binary form has two large sections of roughly equal duration. The first will begin in a certain key, which will often, (but not always), modulate to a closely related key. Pieces in a major key will usually modulate to the dominant, (the fifth scale degree above the tonic). Pieces in a minor key will generally modulate to the relative major key, (the key of the third scale degree above the minor tonic), or to the dominant minor. A piece in minor may also stay in the original key at the end of the first section, closing with an imperfect cadence.

The second section of the piece begins in the newly established key, where it remains for an indefinite period of time. After some harmonic activity, the piece will eventually modulate back to its original key before ending.

More often than not, especially in 18th-century compositions, the A and B sections are separated by double bars with repeat signs, meaning both sections were to be repeated.

Binary form is usually characterized as having the form AB, though since both sections repeat, a more accurate description would be AABB. Others, however, prefer to use the label AA′. This second designation points to the fact that there is no great change in character between the two sections. The rhythms and melodic material used will generally be closely related in each section, and if the piece is written for a musical ensemble, the instrumentation will generally be the same. This is in contrast to the use of verse-chorus form in popular music—the contrast between the two sections is primarily one of the keys used.

Further distinctions ​

A piece in binary form can be further classified according to a number of characteristics:

Simple vs. rounded ​

Occasionally, the B section will end with a "return" of the opening material from the A section. This is referred to as rounded binary, and is labeled as ABA′. In rounded binary, the beginning of the B section is sometimes referred to as the "bridge", and will usually conclude with a half cadence in the original key. Rounded binary is not to be confused with ternary form, also labeled ABA—the difference being that, in ternary form, the B section contrasts completely with the A material as in, for example, a minuet and trio. Another important difference between the rounded and ternary form is that in rounded binary, when the "A" section returns, it will typically contain only half of the full "A" section, whereas ternary form will end with the full "A" section.

Sometimes, as in the keyboard sonatas of Domenico Scarlatti, the return of the A theme may include much of the original A section in the tonic key, so much so that some of his sonatas can be regarded as precursors of sonata form.

Rounded binary form is sometimes referred to as small ternary form.

Rounded binary or minuet form:

A :||: B A or A'
I(->V) :||: V(or other closely related) I

If the B section lacks such a return of the opening A material, the piece is said to be in simple binary.

Simple:

A->B :||: A->B
I->V :||: V->I

Slow-movement form:

A' A"
I->V I->I

Many examples of rounded binary are found among the church sonatas of Vivaldi including his Sonata No. 1 for Cello and Continuo, First Movement, while certain Baroque composers such as Bach and Handel used the form rarely.

Sectional vs. continuous ​

If the A section ends with an Authentic (or Perfect) cadence in the original tonic key of the piece, the design is referred to as a sectional binary. This refers to the fact that the piece is in different tonal sections, each beginning in their own respective keys.

If the A section ends with any other kind of cadence, the design is referred to as a continuous binary. This refers to the fact that the B section will "continue on" with the new key established by the cadence at the end of A.

Symmetrical vs. asymmetrical ​

If the A and B sections are roughly equal in length, the design is referred to as symmetrical.

If the A and B sections are of unequal length, the design is referred to as asymmetrical. In such cases, the B section is usually substantially longer than the A section.

The asymmetrical binary form becomes more common than the symmetrical type from about the time of Beethoven, and is almost routine in the main sections of Minuet and Trio or Scherzo and Trio movements in works from this period. In such cases, occasionally only the first section of the binary structure is marked to be repeated.

Although most of Chopin's nocturnes are in an overall ternary form, quite often the individual sections (either the A, the B, or both) are in binary form, most often of the asymmetrical variety. If a section of this binary structure is repeated, in this case it is written out again in full, usually considerably varied, rather than enclosed between repeat signs.

Balanced binary ​

Balanced binary is when the end of the first section and the end of the second section have analogous material and are organized in a parallel way.

Ternary form ​

Ternary form is a three-part musical form in which the third part repeats or at least contains the principal idea of the first part, represented as A B A. 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.

Ternary form, sometimes called song form, is a three-part musical form consisting of an opening section (A), a following section (B) and then a repetition of the first section (A). It is usually schematized as A–B–A. Prominent examples include the da capo aria "The trumpet shall sound" from Handel's Messiah, Chopin's Prelude in D-Flat Major "Raindrop", (Op. 28) and the opening chorus of Bach's St John Passion.

Simple ternary form ​

In ternary form each section is self-contained both thematically as well as tonally (that is, each section contains distinct and complete themes), and ends with an authentic cadence. The B section is generally in a contrasting but closely related key, usually a perfect fifth above or the parallel minor of the home key of the A section (V or i); however, in many works of the Classical period, the B section stays in tonic but has contrasting thematic material. It usually also has a contrasting character; for example section A might be stiff and formal while the contrasting B section would be melodious and flowing. Da capo aria

Baroque opera arias and a considerable number of baroque sacred music arias was dominated by the Da capo aria which were in the ABA form. A frequent model of the form began with a long A section in a major key, a short B section in a relative minor key mildly developing the thematic material of the A section and then a repetition of the A section. By convention in the third section (the repeat of section A after section B) soloists may add some ornamentation or short improvised variations. In later classical music such changes may have been written into the score. In these cases the last section is sometimes labeled A’ or A1 to indicate that it is slightly different from the first A section.

Compound ternary or trio form ​

In a trio form each section is a dance movement in binary form (two sub-sections which are each repeated) and a contrasting trio movement also in binary form with repeats. An example is the minuet and trio from Haydn's Surprise Symphony. The minuet consists of one section (1A) which is repeated and a second section (1B) which is also repeated. The trio section follows the same format (2A repeated and 2B repeated). The complete minuet is then played again at the end of the trio represented as: [(1A–1A–1B–1B) (2A–2A–2B–2B) (1A–1A–1B–1B)]. By convention in the second rendition of the minuet, the sections are not repeated with the scheme [(1A–1A–1B–1B) (2A–2A–2B–2B) (1A–1B)]. The trio may also be referred to as a double or as I/II, such as in Bach's polonaise and double (or Polonaise I/II) from his second orchestral suite and his bouree and double (or Bouree I/II) from his second English Suite for harpsichord.

The scherzo and trio, which is identical in structure to other trio forms, developed in the late Classical and early Romantic periods. Examples include the scherzo and trio (second movement) from Beethoven's Symphony No. 9 and the scherzo and trio in Schubert's String Quintet. Another name for the latter is "composite ternary form".[citation needed]

Trio form movements (especially scherzos) written from the early romantic era sometimes include a short coda (a unique ending to complete the entire movement) and possibly a short introduction. The second movement of Beethoven's Symphony No. 9 is written in this style which can be diagrammed as [(INTRO) (1A–1A–1B–1B) (2A–2A–2B–2B) (1A–1B) (CODA)]

Marches by John Philip Sousa and others follow this form, and the middle section is called the "trio". Polkas are also often in compound-ternary form.

Quasi compound form ​

Occasionally the A section or B section of a dance like movement is not divided into two repeating parts. For example, in the Minuet in Haydn's String Quartet op. 76 no. 6, the Minuet is in standard binary form (section A and B) while the trio is in free form and not in two repeated sections. Haydn labeled the B section "Alternative", a label used in some Baroque pieces (though most such pieces were in proper compound ternary form).

Ternary form within a ternary form ​

In a complex ternary form each section is itself in ternary form in the scheme of [(A–B–A)(C–D–C)(A–B–A)] By convention each part is repeated and only on its first rendition: [(A–A–B–B–A)(C–C–D–D–C)(A–B–A)]. An example are the Impromptus (Op. 7) by Jan Voříšek.[9]

Expanded ternary forms are especially common among Romantic-era composers; for example, Chopin's "Military" Polonaise (Op. 40, No. 1) is in the form [(A–A–B–A-B–A)(C–C–D–C-D–C)(A–B–A)], where the A and B sections and C and D sections are repeated as a group, and the original theme returning at the end without repeats.

Rondo form ​

Rondo 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 contrast 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 ​

Some forms are used predominantly within popular music, including genre-specific forms. Popular music forms are often derived from strophic form (AAA song form), 32-bar form (AABA song form), verse-chorus form (AB song form) and 12-bar blues form (AAB song form).

Sectional forms ​

• AABA a.k.a. American Popular
• AB a.k.a. Verse/Chorus
  • ABC a.k.a. Verse/Chorus/Bridge
• ABAB
• ABAC a.k.a. Verse/Chorus/Verse/Bridge
• ABCD a.k.a. Through-composed
• Blues Song forms
  • AAB a.k.a. Twelve-bar blues
  • 8-Bar Blues
  • 16-Bar Blues

Extended forms ​

Extended form are forms that have their root in one of the forms above, however, they have been extended with additional sections. For example:

• AAAAA
• AABABA

Compound forms ​

Also called Hybrid song forms. Compound song forms blend together two or more song forms.

Section names in popular music ​

• Introduction a.k.a. Intro
• Verse
• Refrain
• Pre-chorus / Rise / Climb
• Chorus
• Post-chorus
• Bridge
• Middle-Eight
• Solo / Instrumental Break
• Collision
• CODA / Outro
• Ad Lib (Often in CODA / Outro)

Cyclical forms ​

In the 13th century the song cycle emerged, which is a set of related songs (as the suite is a set of related dances). The oratorio took shape in the second half of the 16th century as a narrative recounted—rather than acted—by the singers.

Matrix ​

In music, especially folk and popular music, a matrix is an element of variations which does not change. The term was derived from use in musical writings and from Arthur Koestler's The Act of Creation, who defines creativity as the bisociation of two sets of ideas or matrices. Musical matrices may be combined in any number, usually more than two, and may be — and must be for analysis — broken down into smaller ones. They may be intended by the composer and perceived by the listener, or they may not, and they may be purposefully ambiguous.

The simplest examples given by van der Merwe are fixed notes, definite intervals, and regular beats, while the most complex given are the Baroque fugue, Classical tonality, and Romantic chromaticism. The following examples are some matrices which are part of "Pop Goes the Weasel":

• major mode
• 6/8 time
• four-bar phrasing
• regular beat
• rhyming tune structure
• ending both halves of the tune with the same figure
• melodic climax
• perfect cadence
• three primary triads implied

Co-ordinated matrices may possess "bound-upness" or "at-oddness", depending on the degree to which they are connected to each other or go their separate ways, respectively, and are more or less easy to reconcile. The matrices of the larger matrix known as sonata rondo form are more bound up than the matrices of rondo form, while African and Indian music feature more rhythmic at-oddness than European music's coinciding beats, and European harmony features more at-oddness (between the melody and bass) than the preceding organum. At-oddness is a matter of degree, and almost all at odd matrices are partially bound up.[3]