Song structure

Song structure is the arrangement of a song, and is a part of the songwriting process. It is typically sectional, which uses repeating forms in songs. Common piece-level musical forms for vocal music include bar form, 32-bar form, verse–chorus form, ternary form, strophic form, and the 12-bar blues. Popular music songs traditionally use the same music for each verse or stanza of lyrics (as opposed to songs that are "through-composed"—an approach used in classical music art songs). Pop and traditional forms can be used even with songs that have structural differences in melodies. The most common format in modern popular music is introduction (intro), verse, pre-chorus, chorus, verse, pre-chorus, chorus, bridge, and chorus, with an optional outro. In rock music styles, notably heavy metal music, there are usually one or more guitar solos 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" structure. Some writers use a simple "verse, 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." 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 that repeats. Pop songs may have an introduction and 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 (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 melodically, rhythmically, harmonically and dynamically. Songs in verse–chorus form may also include introductory, transitional and concluding sections.

Introduction

300px|thumb|"[[Jingle Bellss introduction or Structure: Intro, Verse I, Chorus, Verse II, Chorus, Verse III, Chorus, Verse IV, Chorus, Outro.]]

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 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 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, 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" 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 G7 chord. In some cases, an introduction contains only drums or percussion parts that set the rhythm and "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 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===

300px|thumb|"Jingle Bellss verse or

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 prolongs the tonic....The musical structure of the verse nearly always recurs at least once with a different set of lyrics." 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." "A verse exists primarily to support the chorus or refrain...both musically and lyrically." 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–V7 chords. In the key given, ii of G Major would be an A minor chord. V7 of G Major would be D7. 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 D7. 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 D7 chord. There is no D7 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 V7/V or five of five, as the D7 chord is the dominant (or fifth) chord of G Major.

Chorus or refrain

300px|thumb|"Jingle Bells"'s chorus or

The terms chorus and refrain are often used interchangeably, both referring to a recurring part of a song. When a distinction is made, the chorus is the part that contains the hook 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. 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"). 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.

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, but more often refers to a section that has similar character to the chorus, but is distinguishable in close analysis. The concept of a post-chorus has been particularly popularized and analyzed by music theorist Asaf Peres, who is followed in this section. (in Peres's terms, a detached postchorus) or an extension of the chorus (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. the chorus consists of the phrase "the boys are back in town", repeated in a call-and-response style, while the post-chorus features a prominent riff by two lead guitars.

"Smells Like Teen Spirit" (Nirvana, 1991): 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 vocables like "ah" or "oh".

"Shape of You" (Ed Sheeran, 2017): 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): 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. Also "Old MacDonald", "Amazing Grace", "The Thrill Is Gone", and Gordon Lightfoot's "The Wreck of the Edmund Fitzgerald".

AABA may be found in Crystal Gayle's "Don't It Make My Brown Eyes Blue", Billy Joel's "Just the Way You Are", and The Beatles' "Yesterday".

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 Woman" (verse first).

ABABCB format may be found in John Cougar Mellencamp's "Hurts So Good", Tina Turner's "What's Love Got to Do with It?", and ZZ Top's "Sharp Dressed Man".