The_Complete_Idiot%27s_Guide_To_Music_Theory

Bridge
The bridge is kind of a break in the middle of the piece. Most bridges sound
completely different from the verse and chorus, and are often based on a different
harmonic structure. For example, a bridge might be based around the IV
chord instead of the I chord.
Bridges typically are short—only about eight measures. (That’s why a bridge is
sometimes called the “middle eight” of a song.)
Instrumental Solo
If you’re writing a song with lyrics, you might want to give the singer (and the
audience) a break by inserting an instrumental section after the chorus or bridge.
This section should probably be based on the chords of the verse, or maybe the
verse and chorus combined. When the instrumentalist is done soloing, you
return to either the verse or the chorus and pick up the lyric where you left off.
This section is relevant only if you’re writing a song with lyrics; otherwise the
entire song is instrumental!
Ending
The ending isn’t necessarily a separate section of the song. Sometimes you end
the song after the last chorus; either by stopping on the I chord or (if you’re in
a recording studio) fading out the volume. More sophisticated songs have unique
ending sections tacked on to the end of the song, which typically use some sort
of cadence or turnaround (explained in Chapter 16). You might even want the
ending to mirror the song’s intro, or otherwise reflect the melodic or harmonic
nature of the piece.
Putting It All Together
Most popular and jazz music is based on eight-measure phrases. Your verse
might be one eight-measure phrase; your chorus, another. We keep track of the
different parts of a song by assigning them letters—which shouldn’t be confused
with the letters we used to label the notes in a scale. (These letters have nothing
to do with individual notes or pitches.)
The very first eight-measure phrase in your song—which is typically the first
verse—is labeled “A.” If the verse is repeated anywhere in the song, it retains its
“A” labeling.
The second eight-measure phrase—typically the chorus—is labeled “B.” If the
chorus repeats later in the song, the repeated chorus is still labeled “B.”
The third eight-measure phrase—the bridge, if you have one—is labeled “C.”
Additional phrases build on this lettering scheme.
Chapter 11: Phrases and Form 147
Note
An extended chorus played
during the fadeout of a
song is called the out
chorus.
Note
The eight-measure phrase
rule isn’t hard and fast,
although the concept of
being divisible by eight is
somewhat rigidly followed.
This means that, in
addition to the standard
eight-measure phrases, you
can also have 16- and
32-bar phrases, both of
which are divisible by 8.
(Although if a phrase gets
to be 32 bars long, it’s
probably more of a section
than a phrase, if you want
to be technical about it.)