Song structure

"Jingle Bells"'s introduction Play intro^ⓘ or full song^ⓘ 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. The intro also sets the story too.

"Jingle Bells"'s verse Play verse^ⓘ or full song^ⓘ

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."[4] 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."[5] "A verse exists primarily to support the chorus or refrain...both musically and lyrically."[6] A verse of a song, is a repeated sung melody where the words change from use to use (though not necessarily a great deal).

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."[7] 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.

"Jingle Bells"'s chorus Play chorus^ⓘ or full song^ⓘ

The terms chorus and refrain are often used interchangeably,[8] both referring to a recurring part of a song. When a distinction is made, the chorus is the part that contains the hook[9] 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.[5] 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.[6] 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").[10]

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."[11] 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.

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,[12] but more often refers to a section that has similar character to the chorus, but is distinguishable in close analysis.[13] The concept of a post-chorus has been particularly popularized and analyzed by music theorist Asaf Peres, who is followed in this section.[13][12]

Characterizations of post-chorus vary, but are broadly classed into simply a second chorus[14] (in Peres's terms, a detached postchorus) or an extension of the chorus[15] (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.[15]

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:[13] 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:

• "Chandelier" (Sia, 2014):[13][16] 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):[17] 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):[18] 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".[15] Examples include:

• "Umbrella" (Rihanna, 2007):[19] 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.[20]
• "Shape of You" (Ed Sheeran, 2017):[15][16] 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):[13] 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.[13]

A bridge may be a 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."[11] "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."[10] 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.[10]

In music theory, "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-{Verse-Pre-Chorus-Chorus}{Verse-Pre-Chorus-Chorus}-Middle 8-{Chorus}

By adding a powerful upbeat middle eight, musicians can then end the song with a hook in the end chorus and finale.

"Jingle Bells"'s outro Play outro^ⓘ or full song^ⓘ

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 DJs, 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-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 on the mixing board to gradually decrease the volume of the recording. When a tribute band plays a cover song that, in the recorded version ends with a fade-out, the live band may imitate that by playing progressively quieter.

Another way many pop and rock songs end is with a 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 of a few chords that the band repeats. In a jazz song, this could be a standard turnaround, such as I–vi–ii–V⁷ or a stock progression, such as ii–V⁷. 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–V⁷ tag, the bandleader cues the band to do a 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.

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 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.

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 solos are common in rock music, particularly 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 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.

An ad lib section of a song (usually in the coda or 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.