Form is the key that unlocks the musical map of a song or a musical compostition. Like a house has rooms, so a song has rooms or sections.
Chord progressions come in sections, like one room in a house. You can put several different rooms together to make a big house, or you can live in a one room house. Just like people. In most 3rd world countries people live in one room houses -- which means, of course, that much of the world lives in one-room houses.
Those of us who live in the West generally live in multi-room houses.
But there are also musical houses -- we call them songs -- that are built out of several different rooms -- several different chord progressions. Some of them, like mansions and castles, go on and on and get quite involved.
But most songs are like many modest houses -- they have 2 or 3 rooms, sometimes 4 -- built using 2 or 3 or 4 different chord progressions.
Each "room" in a musical house is called a theme, or a "motif". The first theme is always called "A". The next theme is called "B", the next theme is called "C", and so on. Most songs only have 2 or 3 themes, but these themes often repeat.
For example, let's say we have a chord progression that goes like this:
C Am7 Dm7 G7
...and then it repeats those same 4 chords...
and then we have another chord progression that goes like this:
Gm7 C7 F Fm7 Bb7 Eb G7
...and then the first chord progression is used again as the song ends.
This song would have a musical form of A, A, B, A -- main theme, repeat of main theme, contrasting theme, main theme.
If a song went like this:
Theme contrast theme
?it would be known as ABA musical form
If a song went like this:
Theme, theme, contrast, theme
?.then the song would be in AABA musical form
The "B" section of a song is sometimes called the "bridge", or the "release", or the "chorus". These terms usually mean the same thing -- depending upon the form used.
Can you guess what this might be called?
Theme - contrast - theme - contrast - theme - contrast - theme - contrast
Right you are! A B A B form.
This is also known as "verse-chorus" form.
Most popular songs fall into one of these forms:
A B A
A A B A
A B A C A
A B A B
Why should you care?
Because if you know songs are constructed this way, you can look at songs with smart eyes -- you know what to look for, and once you determine the form, you have a "mental map" of the song -- you're not just wandering from chord to chord anymore.
In addition, most songs are proportional. That is -- 4 bars of section A, then 4 bars of section B, then another 4 bars of section A, and so on. You will find TONS and TONS of popular songs that are 32 bars long in A A B A form -- 8 bars of theme A, 8 bars of theme A repeated, then a bridge of 8 bars, finishing with 8 bars of theme A.
Does that give you an advantage knowing that?
It gives you a HUGE advantage because you know what to look for, and you know that if you learn theme A you have automatically learned 75% of the song! All that remains is to learn the 8 bars of the bridge, and you've got it!
And that's why you need to learn about form.
Duane Shinn is the author of over 500 music books and music educational materials such as DVD's, CD's, musical games for kids, chord charts, musical software, and piano lesson instructional courses for adults. His courses have been written up in hundreds of newspapers and magazines. His book-CD-DVD course titled "How To Play Chord Piano" (http://www.chordpiano.com) has sold over 100,000 copies around the world. He holds an advanced degree from Southern Oregon University and was the founder of Piano University in Southern Oregon. He has also logged time as an assistant music therapist, piano tuner, and working piano player. He is the author of the popular free 101-week e-mail newsletter titled "Amazing Secrets Of Exciting Piano Chords & Sizzling Chord Progressions" with over 55,000 current subscribers. Those interested may obtain a free subscription by going to http://www.playpiano.com/