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{{Short description|Arrangement of a song, part of the songwriting process}}
'''Song structure''' is the arrangement of a song,<ref>[https://web.archive.org/web/20190115182419/https://books.google.com.au/books?id=gMJ2DwAAQBAJ&pg=PP12&dq=song+structure&hl=en&sa=X&ved=0ahUKEwihvrzqzu_fAhUITrwKHf4DDMUQ6AEISDAG#v=onepage&q=song%20structure&f=false 5 Quick Steps to Becoming a Music Producer: A music producer's voyage] </ref> and is a part of the [[songwriting]] process. It is typically [[section (music)|section]]al, which uses repeating forms in songs. Common piece-level [[musical form]]s for vocal music include [[bar form]], [[thirty-two-bar form|32-bar form]], [[verse–chorus form]], [[ternary form]], [[strophic form]], and the [[twelve-bar blues|12-bar blues]]. Popular music songs traditionally use the same music for each [[Verse (poetry)|verse]] or [[stanza]] of lyrics (as opposed to songs that are "[[through-composed]]"—an approach used in [[classical music]] [[art song]]s). Pop and traditional forms can be used even with songs that have structural differences in melodies.{{Clarify|date=May 2016}} The most common format in modern popular music is introduction (intro), verse, pre-chorus, chorus, verse, pre-chorus, chorus, [[Bridge (music)|bridge]], and chorus, with an optional outro. In rock music styles, notably [[heavy metal music]], there is usually one or more [[guitar solo]]s in the song, often found after the middle chorus part. In pop music, there may be a guitar solo, or a solo performed with another instrument such as a [[synthesizer]] or a [[saxophone]].

The foundation of popular music is the "verse" and "[[chorus (song)|chorus]]" structure. Some writers use a simple "verse, [[Hook (music)|hook]], verse, hook, bridge, hook" method. Pop and rock songs nearly always have both a verse and a chorus. The primary difference between the two is that when the music of the verse returns, it is almost always given a new set of lyrics, whereas the chorus usually retains the same set of lyrics every time its music appears."<ref>[[Walter Everett (musicologist)|Everett, Walter]] (2008). ''The Foundations of Rock : From "Blue Suede Shoes" to "Suite: Judy Blue Eyes": From "Blue Suede Shoes" to "Suite: Judy Blue Eyes"'', p.145. {{ISBN|9780199718702}}.</ref> Both are essential elements, with the verse usually played first (exceptions include "[[She Loves You]]" by [[The Beatles]], an early example in the [[rock music]] genre). Each verse usually employs the same melody (possibly with some slight modifications), while the lyrics usually change for each verse. The chorus (or "refrain") usually consists of a melodic and lyrical [[phrase (music)|phrase]] that repeats. Pop songs may have an [[Introduction (music)|introduction]] and [[coda (music)|coda]] ("tag"), but these elements are not essential to the identity of most songs. Pop songs often connect the verse and chorus via a pre-chorus, with a bridge section usually appearing after the second chorus.

The verse, chorus and pre-chorus are usually repeated throughout a song, while the intro, bridge, and [[Coda (music)|coda]] (also called an "outro") are usually only used once. Sometimes a post-chorus will be present on a song. Some pop songs may have a solo section, particularly in rock or blues-influenced pop. During the solo section, one or more instruments play a melodic line which may be the melody used by the singer, or, in blues or jazz improvised.

==Verse–chorus form==

[[Verse–chorus form]] consists of two main sections – a verse and chorus – that often contrast [[melody|melodically]], [[rhythm]]ically, [[harmony|harmonically]] and [[dynamics (music)|dynamically]].<ref>[http://www.mtosmt.org/issues/mto.11.17.3/mto.11.17.3.doll.html Doll, Christopher. "Rockin' Out: Expressive Modulation in Verse–Chorus Form", ''Music Theory Online'' 17/3 (2011), §&nbsp;2.]</ref> Songs in verse–chorus form may also include introductory, transitional and concluding sections.

===Introduction===
{{Unreferenced section|date=February 2020}}
[[File:Jingle Bells intro Ab.png|300px|thumb|"[[Jingle Bells]]{{" '}}s introduction {{audio|Jingle Bells intro Ab.mid|Play intro}} or {{audio|Jingle Bells full Ab.mid|full song}} Structure: Intro, Verse I, Chorus, Verse II, Chorus, Verse III, Chorus, Verse IV, Chorus, Outro.]]
{{Main article|Introduction (music)}}
The introduction is a unique section that comes at the beginning of the piece. Generally speaking, an introduction contains just music and no words. It usually builds up suspense for the listener so when the [[Beat (music)#Downbeat and upbeat|downbeat]] drops in, it creates a pleasing sense of release. The intro also creates the atmosphere of the song. As such, the [[rhythm section]] typically plays in the "feel" of the song that follows. For example, for a blues shuffle, a band starts playing a shuffle rhythm. In some songs, the intro is one or more bars of the [[Tonic (music)|tonic]] [[Chord (music)|chord]] (the "home" key of the song). With songs, another role of the intro is to give the singer the key of the song. For this reason, even if an intro includes chords other than the tonic, it generally ends with a [[cadence (music)|cadence]], either on the tonic or dominant chord.

The introduction may also be based around the chords used in the verse, chorus, or bridge, or a stock "[[Turnaround (music)|turnaround]]" progression may be played, such as the I–vi–ii–V progression (particularly in jazz influenced pop songs). More rarely, the introduction may begin by suggesting or implying another key. For example, a song in C Major might begin with an introduction in G Major, which makes the listener think that the song will eventually be in G Major. A cliche used to indicate to the listener that this G Major section is in fact the [[dominant chord]] of another key area is to add the [[dominant seventh]], which in this case would shift the harmony to a G<sup>7</sup> chord. In some cases, an introduction contains only drums or percussion parts that set the [[rhythm]] and [[Groove (music)|"groove"]] for the song. Alternately the introduction may consist of a solo section sung by the lead singer (or a group of backup singers), or a [[riff (music)|riff]] played by an instrumentalist.

The most straightforward, and least risky way to write an introduction is to use a section from the song. This contains melodic themes from the song, chords from one of the song's sections, and the beat and style of the song. However, not all songs have an intro of this type. Some songs have an intro that does not use any of the material from the song that is to follow. With this type of intro, the goal is to create interest in the listener and make them unsure of what will happen. This type of intro could consist of a series of loud, accented chords, punctuated by cymbal, with a bassline beginning near the end, to act as a pitch reference point for the singer.

===Verse===<!--[[Verse (popular music)]] redirects directly here-->
[[File:Jingle Bells verse Ab.png|300px|thumb|"Jingle Bells{{"'}}s verse {{audio|Jingle Bells verse Ab.mid|Play verse}} or {{audio|Jingle Bells full Ab.mid|full song}}]]
{{Main article|Verse–chorus form}}
In popular music, a '''verse''' roughly corresponds to a poetic ''[[stanza]]'' because it consists of rhyming lyrics most often with an AABB or ABAB [[rhyme scheme]]. When two or more sections of the song have almost identical music but different lyrics, each section is considered one verse.

Musically, "the verse is to be understood as a unit that [[prolongation|prolongs]] the [[tonic (music)|tonic]]....The musical structure of the verse nearly always recurs at least once with a different set of lyrics."<ref>Everett, Walter (1999). ''The Beatles as Musicians: Revolver Through the Anthology'', p.15. Oxford University Press. {{ISBN|9780195129410}}.</ref> The tonic or "home key" chord of a song can be prolonged in a number of ways. Pop and rock songs often use chords closely related to the tonic, such as iii or vi, to prolong the tonic. In the key of C Major, the iii chord would be E Minor and the vi chord would be A Minor. These chords are considered closely related to the tonic because they share chord tones. For example, the chord E Minor includes the notes '''E''' and '''G''', both of which are part of the C Major triad. Similarly, the chord A Minor includes the notes '''C''' and '''E''', both part of the C Major triad.

Lyrically, "the verse contains the details of the song: the story, the events, images and emotions that the writer wishes to express....Each verse will have different lyrics from the others."<ref name="D&H6">Davidson, Miriam; Heartwood, Kiya (1996). ''Songwriting for Beginners'', p.6. Alfred Music Publishing. {{ISBN|0739020005}}.</ref> "A verse exists primarily to support the chorus or refrain...both musically and lyrically."<ref name="Cope68"/> A verse of a song, is a repeated sung melody where the words change from use to use (though not necessarily a great deal).

===Pre-chorus===<!--[[Pre-chorus]] redirects directly here-->
An optional section that may occur after the verse is the '''pre-chorus'''. Also known as a "'''build'''", "'''channel'''", or "'''transitional bridge'''", the pre-chorus functions to connect the verse to the chorus with intermediary material, typically using [[subdominant]] (usually built on the IV chord or ii chord, which in the key of [[C Major]] would be an [[F Major]] or [[D minor]] chord) or similar transitional harmonies. "Often, a two-phrase verse containing basic chords is followed by a passage, often harmonically probing, that leads to the full chorus."<ref>Everett (2008), p.146.</ref> Often, when verse and chorus use the same harmonic structure, the pre-chorus introduces a new harmonic pattern or harmony that prepares the verse chords to transition into the chorus.

For example, if a song is set in C Major, and the songwriter aims to get to a chorus that focuses on the dominant chord ([[G Major]]) being tonicized (treated like a "home key" for a short period), a chord progression could be used for the pre-chorus that gets the listener ready to hear the chorus' chord (G Major) as an arrival key. One widely used way to accomplish this is to precede the G Major chord with its own ii–V<sup>7</sup> chords. In the key given, ii of G Major would be an [[A minor]] chord. V<sup>7</sup> of G Major would be D<sup>7</sup>. As such, with the example song, this could be done by having a pre-chorus that consists of one bar of A minor and one bar of D<sup>7</sup>. This would allow the listener to expect a resolution from ii–V to I, which in this case is the temporary tonic of G Major. The chord A minor would not be unusual to the listener, as it is a shared chord that exists in both G Major and C Major. A minor is the ii chord in G Major, and it is the vi chord in C Major. The chord that would alert the listener that a change was taking place is the D<sup>7</sup> chord. There is no D<sup>7</sup> chord in C Major. A listener experienced with popular and traditional music would hear this as a [[secondary dominant]]. Harmonic theorists and arrangers would call it V<sup>7</sup>/V or ''five of five'', as the D<sup>7</sup> chord is the dominant (or fifth) chord of G Major.

===Chorus or refrain===
[[File:Jingle Bells chorus Ab.png|300px|thumb|"Jingle Bells"'s chorus {{audio|Jingle Bells chorus Ab.mid|Play chorus}} or {{audio|Jingle Bells full Ab.mid|full song}}]]
{{main article|Refrain}}

The terms ''chorus'' and ''refrain'' are often used interchangeably,<ref>Whitesell, Lloyd (2008). ''The Music of Joni Mitchell'', p.151. {{ISBN|9780199719099}}.</ref> both referring to a recurring part of a song. When a distinction is made, the chorus is the part that contains the hook<ref name="Watson">Watson, C. J. (2003). ''The Everything Songwriting Book: All You Need to Create and Market Hit Songs'', p.86. Adams Media. {{ISBN|9781440522666}}.</ref> or the "main idea" of a song's lyrics and music, and there is rarely variation from one repetition of the chorus to the next.<ref name="D&H6"/> A refrain is a repetitive phrase or phrases that serve the function of a chorus lyrically, but are not in a separate section or long enough to be a chorus.<ref name="Cope68">Cope (2009), p.68.</ref> For example, refrains are found in [[the Beatles]]' "[[She Loves You]]" ("yeah, yeah, yeah"), [[AC/DC]]'s "[[You Shook Me All Night Long]]", [[Simon & Garfunkel]]'s "[[The Sound of Silence]]", and "[[Deck the Halls]]" ("fa la la la la").<ref name="D&H7"/>

The chorus or refrain is the element of the song that repeats at least once both musically and lyrically. It is always of greater musical and emotional intensity than the verse. "The chorus, which gets its name from a usual thickening of texture from the addition of backing vocals, is always a discrete section that nearly always prolongs the tonic and carries an unvaried poetic text."<ref name="Everett16">Everett (1999), p.16.</ref> In terms of narrative, the chorus conveys the main message or theme of the song. Normally the most memorable element of the song for listeners, the chorus usually contains the [[Hook (music)|hook]].<ref name="songstuff">{{cite web |title=Song Building Blocks |date=14 March 2025 |url=https://www.songstuff.com/songwriting/article/song_building_blocks/ |work=Songstuff}}</ref>



===Post-chorus===
{{main|Post-chorus}}
An optional section that may occur after the chorus is the '''post-chorus''' (or '''postchorus'''). The term can be used generically for any section that comes after a chorus,<ref name="sloan-harding-2019">{{cite book |title=[[Switched on Pop]]: How Popular Music Works, and Why it Matters |first1=Nate |last1=Sloan |first2=Charlie |last2=Harding |year=2019 |isbn=9780190056674 |publisher=Oxford University Press |page=[https://books.google.com/books?id=s_C9DwAAQBAJ&dq=post-chorus&pg=PA51 51]}}</ref> but more often refers to a section that has similar character to the chorus, but is distinguishable in close analysis.<ref name="peres">{{cite web |url=https://www.top40theory.com/blog/everything-you-need-to-know-about-the-postchorus |title=Everything You Need to Know About the Postchorus |date=2018-07-31 |first=Asaf |last=Peres |work=Top40 Theory}}</ref> The concept of a post-chorus has been particularly popularized and analyzed by music theorist Asaf Peres, who is followed in this section.<ref name="peres"/><ref name="sloan-harding-2019"/>

Characterizations of post-chorus vary, but are broadly classed into simply a second chorus<ref name="zeger">{{cite web |title=The Post-Chorus, And It's [sic] Unsung Place In Pop Music |date=2016-08-17 |first=Eli |last=Zeger |url=https://magazine.vinylmeplease.com/magazine/post-chorus/ |work=Vinyl Me, Please.}}</ref> (in Peres's terms, a ''detached postchorus'') or an extension of the chorus<ref name="blume">{{cite web |title=The Power of Post-Choruses |date=2018-04-02 |first=Jason |last=Blume |url=https://www.bmi.com/news/entry/the-power-of-post-choruses |work=Broadcast Music, Inc. (BMI)}}</ref> (in Peres's terms, an ''attached postchorus''). Some restrict "post-chorus" to only cases where it is an extension of a chorus (attached postchorus), and do not consider the second part of two-part choruses (detached postchorus) as being a "post"-chorus.<ref name="blume"/>

As with distinguishing the pre-chorus from a verse, it can be difficult to distinguish the post-chorus from the chorus. In some cases they appear separately – for example, the post-chorus only appears after the second and third chorus, but not the first – and thus are clearly distinguishable. In other cases they always appear together, and thus a "chorus + post-chorus" can be considered a subdivision of the overall chorus, rather than an independent section.

Characterization of a post-chorus varies, beyond "comes immediately after the chorus"; Peres characterizes it by two conditions:<ref name="peres"/> it maintains or increases sonic energy, otherwise it is a bridge or verse; and contains a melodic hook (vocal or instrumental), otherwise it is a transition.

Detached post-choruses typically have distinct melody and lyrics from the chorus:
* <!-- Widely-cited example. -->"[[Chandelier (song)|Chandelier]]" ([[Sia]], 2014):<ref name="peres"/><ref name="keys"/> the chorus begins and ends with "I'm gonna swing from the chandelier / From the chandelier", while the post-chorus repeats instead "holding on", in "I'm holding on for dear life" and "I'm just holding on for tonight", and has a new melody, but the same chord progression as the chorus.
* "[[The Boys Are Back in Town]]" ([[Thin Lizzy]], 1976):<ref>{{Cite web |title=The Post-Chorus, And It's Unsung Place In Pop Music |url=https://www.vinylmeplease.com/blogs/magazine/post-chorus |access-date=2022-05-20 |website=Vinyl Me, Please |language=en}}</ref> the chorus consists of the phrase "the boys are back in town", repeated in a [[Call and response (music)|call-and-response]] style, while the post-chorus features a prominent riff by two lead guitars.
* "[[Smells Like Teen Spirit]]" ([[Nirvana (band)|Nirvana]], 1991):<ref>{{Cite web |title=Verse-Chorus Form |url=https://musictheory.pugetsound.edu/mt21c/VerseChorusForm.html |access-date=2022-05-20 |website=musictheory.pugetsound.edu}}</ref> the chorus lasts from "With the lights out, it's less dangerous" to "A mosquito, my libido", while the post-chorus features a heavy riff with the vocals "hey, yay".

Lyrics of attached post-choruses typically repeat the hook/refrain from the chorus, with little additional content, often using [[Non-lexical vocables in music|vocables]] like "ah" or "oh".<ref name="blume"/> Examples include:
* <!-- Early example, #1 (Billboard Hot 100) -->"[[Umbrella (song)|Umbrella]]" ([[Rihanna]], 2007):{{sfn|von Appen|Frei-Hauenschild|2015|p=79}} the chorus begins "When the sun shine, we shine together" and run through "You can stand under my umbrella / You can stand under my umbrella, ella, ella, eh, eh, eh", which is followed by three more repetitions of "Under my umbrella, ella, ella, eh, eh, eh", the last one adding another "eh, eh-eh". Here the division between chorus and post-chorus is blurred, as the "ella, ella" begins in the chorus, and was a play on the reverb effect.<ref>{{cite magazine |title=The-Dream on Penning Rihanna's 'Umbrella' Hook: 'It Just Never Stopped Pouring, Metaphor After Metaphor' |date=2017-04-28 |first=Adelle |last=Platon |magazine=[[Billboard (magazine)|Billboard]] |url=https://www.billboard.com/articles/columns/hip-hop/7775693/the-dream-rihanna-umbrella-best-choruses-21st-century}}</ref>
* <!-- Typical, widely-cited example, #1 (Billboard Hot 100) -->"[[Shape of You]]" ([[Ed Sheeran]], 2017):<ref name="blume"/><ref name="keys">{{cite book |title=The Craft of Songwriting: Music, Meaning, & Emotion |first=Scarlet |last=Keys |year=2018 |isbn=9781540039965 |publisher=Berklee Press |page=[https://books.google.com/books?id=g_51DwAAQBAJ&pg=PA109 109]}}</ref> the chorus runs "I'm in love with the shape of you ... Every day discovering something brand new / I'm in love with your body", and the post-chorus repeats vocables and the hook "Oh—I—oh—I—oh—I—oh—I / I'm in love with your body", then repeats the end of the chorus, switching "your body" to "the shape of you": "Every day discovering something brand new / I'm in love with the shape of you"
* "[[Girls Like You]]" ([[Maroon 5]], 2018):<ref name="peres"/> the chorus runs "'Cause girls like you ... I need a girl like you, yeah, yeah ... I need a girl like you, yeah, yeah", and the post-chorus repeats the hook with added "yeah"s: "Yeah, yeah, yeah, yeah, yeah, yeah / I need a girl like you, yeah, yeah / Yeah yeah yeah, yeah, yeah, yeah / I need a girl like you".

Hybrids are also common (Peres: ''hybrid postchorus''), where the post-chorus keeps the hook from the chorus (like an attached postchorus), but introduces some additional content (hook or melody, like a detached postchorus.<ref name="peres"/>

===Bridge===
{{main article|Bridge (music)}}

A bridge may be a ''[[transition (music)|transition]]'', but in popular music, it more often is "...a section that contrasts with the verse...[,] usually ends on the dominant...[,] [and] often culminates in a strong re-transitional."<ref name="Everett16"/> "The bridge is a device that is used to break up the repetitive pattern of the song and keep the listener's attention....In a bridge, the pattern of the words and music change."<ref name="D&H7">Davidson & Heartwood (1996), p.7.</ref> For example, [[John Denver]]'s "[[Country Roads]]" is a song with a bridge while [[Stevie Wonder]]'s "[[You Are the Sunshine of My Life]]" is a song without one.<ref name="D&H7"/>

In [[music theory]], "[[Thirty-two-bar form#Middle eight|middle eight]]" (a common type of bridge) refers to a section of a song with a significantly different [[melody]] and lyrics, which helps the song develop itself in a natural way by creating a contrast to the previously played, usually placed after the second chorus in a song.

A song employing a middle eight might look like:
        ....  ....    ....  ....    ........  ....     ....
 Intro-<nowiki/>{Verse-Pre-Chorus-Chorus}{Verse-Pre-Chorus-Chorus}-Middle 8-<nowiki/>{Chorus}<nowiki/>

By adding a powerful upbeat middle eight, musicians can then end the song with a [[hook (music)|hook]] in the end chorus and finale.

===Conclusion or outro===
{{Unreferenced section|date=February 2020}}
[[File:Jingle Bells outro Ab.png|thumb|300px|"Jingle Bells"'s outro {{audio|Jingle Bells outro Ab.mid|Play outro}} or {{audio|Jingle Bells full Ab.mid|full song}}]]
{{Main article|Outro (music)}}

The '''conclusion''' or (in popular-music terminology) '''outro''' of a song is a way of finishing or completing the song. It signals to the listeners that the song is nearing its close. The reason for having an outro is that if a song just ended at the last bar of a section, such as on the last verse or the last chorus, this might feel too abrupt for listeners. By using an outro, the songwriter signals that the song is, in fact, nearing its end. This gives the listeners a good sense of closure. For [[DJ]]s, the outro is a signal that they need to be ready to mix in their next song.

In general, songwriters and arrangers do not introduce any new melodies or riffs in the outro. However, a melody or riff used throughout the song may be re-used as part of an outro. Generally, the outro is a section where the energy of the song, broadly defined, dissipates. For example, many songs end with a [[Fade (audio engineering)|fade-out]], in which the song gets quieter and quieter. In many songs, the band does a [[ritardando]] during the outro, a process of gradually slowing down the tempo. Both the fade-out and the ritardando are ways of decreasing the intensity of a song and signalling that it is nearing its conclusion.

For an outro that fades out, the arranger or songwriter typically repeats a short section of the music over and over. This can be the chorus, for example. An [[audio engineer]] then uses the [[fader (audio engineering)|fader]] on the [[audio console|mixing board]] to gradually decrease the volume of the recording. When a band, especially a [[tribute band]], plays a [[cover song]] that, in the [[recording studio|recorded version]], ended with a fade-out, the live band might simulate that by playing progressively quieter. However, the live band will more likely invent an instrumental ending to definitively finish the song, which may be some standard closing cadence or perhaps a coda specifically patterned after the song's refrain.

Besides fading out, another way some pop and rock songs may end is with a [[Conclusion (music)|tag]]. There are two types of tags: the instrumental tag and the instrumental/vocal tag. With an instrumental tag, the vocalist no longer sings, and the band's [[rhythm section]] takes over the music to finish off the song. A tag is often a [[vamp (music)|vamp]] of a few chords that the band repeats. In a jazz song, this could be a standard [[Turnaround (music)|turnaround]], such as I–vi–ii–V<sup>7</sup> or a stock progression, such as ii–V<sup>7</sup>. If the tag includes the tonic chord, such as a vamp on I–IV, the bandleader typically cues the last time that the penultimate chord (a IV chord in this case) is played, leading to an ending on the I chord. If the tag does not include the tonic chord, such as with a ii–V<sup>7</sup> tag, the bandleader cues the band to do a [[cadence (music)|cadence]] that resolves onto the tonic (I) chord. With an instrumental and vocal tag, the band and vocalist typically repeat a section of the song, such as the chorus, to give emphasis to its message. In some cases, the vocalist may use only a few words from the chorus or even one word. Some bands have the guitar player do a [[guitar solo]] during the outro, but it is not the focus of the section; instead, it is more to add interesting improvisation. A guitar solo during an outro is typically mixed lower than a mid-song guitar solo.

===Elision===
{{Unreferenced section|date=February 2020}}
An elision is a section of music where different sections overlap one another, usually for a short period. It is mostly used in fast-paced music, and it is designed to create tension and drama. Songwriters use elision to keep the song from losing its energy during [[cadence (music)|cadences]], the points at which the music comes to rest on, typically on a tonic or dominant chord. If a song has a section that ends with a cadence on the tonic, if the songwriter gives this cadence a full bar, with the chord held as a whole note, this makes the listener feel like the music is stopping. However, if songwriters use an [[elided cadence]], they can bring the section to a cadence on the tonic, and then, immediately after this cadence, begin a new section of music which overlaps with the cadence. Another form of elision would, in a chorus later in the song, to interject musical elements from the bridge.

===Instrumental solo===
{{Unreferenced section|date=February 2020}}
{{Main article|Solo (music)}}
A solo is a section designed to showcase an instrumentalist (e.g. a guitarist or a harmonica player) or less commonly, more than one instrumentalist (e.g., a trumpeter and a sax player). [[Guitar solo]]s are common in [[rock music]], particularly [[heavy metal music|heavy metal]] and in the [[blues]]. The solo section may take place over the chords from the verse, chorus, or bridge, or over a standard solo backing progression, such as the [[twelve-bar blues|12-bar blues]] progression. In some pop songs, the solo performer plays the same melodies that were performed by the lead singer, often with flourishes and embellishments, such as riffs, scale runs, and arpeggios. In blues- or jazz-influenced pop songs, the solo performers may improvise a solo.

===Ad lib===
{{Unreferenced section|date=February 2020}} 
An ''[[ad libitum|ad lib]]'' section of a song (usually in the [[Coda (music)|coda]] or [[Conclusion (music)|outro]]) occurs when the main lead vocal or a second lead vocal breaks away from the already established lyric and/or melody to add melodic interest and intensity to the end of the song. Often, the ad lib repeats the previously sung line using variations on phrasing, melodic shape, and/or lyric, but the vocalist may also use entirely new lyrics or a lyric from an earlier section of the song. During an ad lib section, the rhythm may become freer (with the rhythm section following the vocalist), or the rhythm section may stop entirely, giving the vocalist the freedom to use whichever tempo sounds right. During live performances, singers sometimes include ad libs not originally in the song, such as making a reference to the town of the audience or customizing the lyrics to the current events of the era.

There is a distinction between ad lib as a song section and ad lib as a general term. Ad lib as a general term can be applied to any free interpretation of the musical material.

==AABA form==
{{Unreferenced section|date=February 2020}} 
{{Main article|Thirty-two-bar form}}
Thirty-two-bar form uses four sections, most often eight measures long each (4×8=32), two verses or A sections, a contrasting B section (the bridge or "middle-eight") and a return of the verse in one last A section (AABA). The B section  is often intended as a contrast to the A sections that precede and follow it. The B section may be made to contrast by putting it in a new harmony. For example, with the [[jazz standard]] "[[I Got Rhythm]]", the A sections are all tonic prolongations based around the I–vi–ii–V [[chord progression]] (B{{music|flat}} in the standard key); however, the B section changes key and moves to V/vi, or D<sup>7</sup> in the standard key, which then does a [[circle of fifths]] movement to G<sup>7</sup>, C<sup>7</sup> and finally F<sup>7</sup>, setting the listener up for a return to the tonic Bb in the final A section.

The "I Got Rhythm" example also provides contrast because the harmonic rhythm changes in the B section. Whereas the A sections contain a vibrant, exciting feel of two chord changes per bar (e.g., the first two bars are often B{{music|flat}}–g minor/c minor–F<sup>7</sup>), the B section consists of two bars of D<sup>7</sup>, two bars of G<sup>7</sup>, two bars of C<sup>7</sup> and two bars of F<sup>7</sup>. In some songs, the "feel" also changes in the B section. For example, the A sections may be in swing feel, and the B section may be in Latin or Afro-Cuban feel.

While the form is often described as AABA, this does not mean that the A sections are all exactly the same. The first A section ends by going back to the next A section, and the second A section ends and transitions into the B section. As such, at the minimum, the composer or arranger often modifies the harmony of the end of the different A sections to guide the listener through the key changes. As well, the composer or arranger may re-harmonize the melody on one or more of the A sections, to provide variety. Note that with a reharmonization, the melody does not usually change; only the chords played by the [[accompaniment]] musicians change.

Examples include "[[Deck the Halls]]":
:A: Deck the hall with boughs of holly,
:A: 'Tis the season to be jolly.
:B: Don we now our gay apparel,
:A: Troll the ancient Yuletide carol.

==Variation on the basic structure==
Verse-chorus form or ABA form may be combined with AABA form, in compound AABA forms. That means that every A section or B section can consist of more than one section (for example Verse-Chorus). In that way the modern popular song structure can be viewed as a AABA form, where the B is the bridge.

AAA format may be found in [[Bob Dylan]]'s "[[The Times They Are a-Changin' (song)|The Times They Are a-Changin']]", and songs like "[[The House of the Rising Sun]]", and "[[Oh My Darling, Clementine|Clementine]]".<ref name="D&H8">Davidson & Heartwood (1996), p.8.</ref> Also "[[Old MacDonald Had a Farm|Old MacDonald]]", "[[Amazing Grace]]", "[[The Thrill Is Gone]]", and [[Gordon Lightfoot]]'s "[[The Wreck of the Edmund Fitzgerald|The Wreck of the ''Edmund Fitzgerald'']]".<ref>Watson (2003), p.87-8.</ref>

AABA may be found in [[Crystal Gayle]]'s "[[Don't It Make My Brown Eyes Blue]]", [[Billy Joel]]'s "[[Just the Way You Are (Billy Joel song)|Just the Way You Are]]", and [[The Beatles]]' "[[Yesterday (Beatles song)|Yesterday]]".<ref>Watson (2003), p.89.</ref>

ABA (verse/chorus or chorus/verse) format may be found in [[Pete Seeger]]'s "[[Turn! Turn! Turn!]]" (chorus first) and [[The Rolling Stones]]'s "[[Honky Tonk Women|Honky Tonk Woman]]" (verse first).<ref name="D&H8"/>

ABAB may be found in AC/DC's "[[Back in Black (song)|Back in Black]]", [[Jimmy Buffett]]'s "[[Margaritaville]]", [[The Archies]]'s "[[Sugar, Sugar]]", and [[The Eagles]]'s "[[Hotel California]]".<ref name="Watson90">Watson (2003), p.90.</ref>

ABABCB format may be found in  [[John Cougar Mellencamp]]'s "[[Hurts So Good]]", [[Tina Turner]]'s "[[What's Love Got to Do with It (song)|What's Love Got to Do with It?]]", and [[ZZ Top]]'s "[[Sharp Dressed Man]]".<ref name="Watson90" /> Variations include [[Smokey Robinson]]'s "[[My Guy]]", [[The Beatles]]'s "[[Ticket to Ride (song)|Ticket to Ride]]",<ref name="D&H8" />  [[The Pretenders]]' "[[Back on the Chain Gang]]" (ABABCAB), [[Poison (American band)|Poison]]'s "[[Every Rose Has Its Thorn]]" (ABABCBAB), and Billy Joel's "[[It's Still Rock and Roll to Me]]" (ABABCABCAB).<ref name="Watson90"/>

==See also==
{{Div col}}
* [[Earworm]] 
* [[Lick (music)|Lick]]
* [[Ostinato]]
* [[Subject (music)|Subject]] 
* [[Vamp (music)|Vamp]]
{{Div col end}}

==References==
{{reflist}}

==Further reading==
{{refbegin}}
* Appen, Ralf von / Frei-Hauenschild, Markus [http://www.gfpm-samples.de/Samples13/appenfrei.pdf "AABA, Refrain, Chorus, Bridge, Prechorus — Song Forms and their Historical Development"]. In: ''Samples. Online Publikationen der Gesellschaft für Popularmusikforschung/German Society for Popular Music Studies e.V.'' Ed. by Ralf von Appen, [[André Doehring]] and [[Thomas Phleps]]. Vol. 13 (2015). 
*Covach, John. "Form in Rock Music: A Primer", in Stein, Deborah (2005). ''Engaging Music: Essays in Music Analysis''. New York: Oxford University Press. {{ISBN|0-19-517010-5}}.
*Covach, John and Boone, Graham, eds. ''Understanding Rock: Essays in Musical Analysis''. Cited in Covach (2005).
*Everett, Walter, ed. ''Rock Music: Critical Essays on Composition, Performance, Analysis, and Reception''. Cited in Covach (2005).
* Forte, Allan ''The American Popular Ballad of the Golden Era, 1924–1950: A Study in Musical Design'', Princeton University Press, 1995. {{ISBN|978-0-691-04399-9}}.
* Kaiser, Ulrich [http://storage.gmth.de/zgmth/pdf/588 "Babylonian confusion. Zur Terminologie der Formanalyse von Pop- und Rockmusik"]. In: ''Zeitschrift der Gesellschaft für Musiktheorie'' 8/1 (2011) – ISSN 1862-6742.
*[[Richard Middleton (musicologist)|Middleton, Richard]]. "Form", in Horner, Bruce and Swiss, Thomas, eds. (1999) ''Key Terms in Popular Music and Culture''. Malden, Massachusetts. {{ISBN|0-631-21263-9}}.
* {{citation |title=The Structure, Function, and Genesis of the Prechorus |first=Jay |last=Summach |url=https://mtosmt.org/issues/mto.11.17.3/mto.11.17.3.summach.html |journal=[[Music Theory Online]] |year=2011 |volume=17 |issue=3 |doi=10.30535/mto.17.3.2 |doi-access=free }}

{{Refend}}

{{Musical form}}
{{Singing}}

[[Category:Popular music]]
[[Category:Song forms| ]]