An Easy Guide to Understanding Chord Progressions;
Also a Brief History on all of Western Music
In western music, we use triads, deal with it. Triad means three, hence three notes, simple.
You’re learning music and increasing your vocabulary, look at you. This is a triad:
… a C-Major triad, playing a whole note, on a treble clef staff...in 4/4 time. If this is completely foreign to you, what follows may be too advanced. If you understand at least most of what I said just now, you’re probably going to be fine, I believe in you.
The black note is the root and therefore the most important. It’s how we define the chord.
The red note is the third and next important. It determines the quality of the chord, major or minor.
The green note is the fifth and least important note in the triad; but still helpful to provide stability.
Again, I’m assuming you know most of this already and how it works, just laying some groundwork for the next bits.
Pick a chord! No don’t, that’s asking too much, I don’t have all day. We’re using C-Major, don’t act surprised. This is our tonic, our home base, the place where we journey from and ultimately return to after pawning that gimp suit that didn’t fit. From there, we’ll discuss minor and then you can pick any key you damn well please.
If you’re going to make a chord progression, it means you’re going to have to make these notes move. Make them do something, force them to be more active than my non-existent fitness regiment. If you’d believe it, pretty much all of your choices boil down to one of two options, tried and true all the way Bach to the days of back…
...I’ll see myself out.
I - V and I - IV
Look at this sexy stack of triads. It’s functionally and ethereally beautiful in its simplicity. A stack of seven notes split into three chords that represent all of the notes available in the C-Major scale.
The black triad is the C-Major, or tonic, or “I” (one) chord.
This also determines the key of your piece, which in this instance is the key of C.
C Major to be specific, and not in a mode, well Ionian mode, we’ll get to that later.
The green triad is the G-Major, or dominant, or “V” (five) chord.
The red triad is the F-Major, or dominant, or “IV” (four) chord.
Any movement that we discuss below is that of only a single scale degree per note, assuming that it results in a new triad. Anything non-triadic (sus chords/quintal) will be discussed later.
I - V
See how that green triad just stacks deliciously on top of the black one (img2)? We love stacking shit up in thirds, and for reasons that you don’t need to understand, this is the science that makes music work. If we move from the I to the V we make that I triad move as much as possible while still being super lazy.
The C moves down to a B.
This action changes the root note and by definition must change the value of the chord.
The E moves down to a D.
This action changes the second most important note. By moving this note, it also creates a more drastic change than by moving just the C (two changes is bigger than one, what?!)
The G doesn’t move at all.
The G, as mentioned before, is the least important note of the triad as the 5th. Therefore, this note changing is less impactful than changing the root or third. By keeping this note the same, we also allow the ear to hear a common tone between the two chords, which helps the movement sound more natural and pleasing. This G becomes the root of the V.
You can see in img3 how the notes move and that if we take the bottom two red notes and move them up an octave, we retain our triad stack. Since this progression changes the root of the chord, I’m going to call it “Journey” movement. Remember this for later.
I - IV
See how that red triad just stacks deliciously underneath the black one? We’re still stacking shit but now we’re going down from the root instead of up. I know I said something about stacking up earlier, but just go with it. If we move from the I to the IV we make that I triad move just as much as the V chord did while still being super lazy.
The E moves up to an F.
This action changes the third of the C into the root of the F, or IV chord.
The G moves up to an A.
This action changes the least important note of the C into the third of the F chord.
The C doesn’t move at all.
In this instance, the root of the I, or tonic chord, has remained unchanged after moving to the F chord. This functions similarly to the G in the I - V in that it retains a common note between the two chords, helping to ease the transition. It differentiates in that the root of the prior chord carries over into the new chord.
Since this progression does not change the root of the tonic chord, I’m going to call it “Home” movement...and that’s pretty much it.
Literally all variations and augmentations that we will use to build more complex chord progressions function off this foundation of two movement types, “Journey” chords and “Home” chords.
Journey chords are used to move the melody/chord progression/song/your amazing and totally original idea away from home base.
Home chords are the opposite of Journey chords. They are used instead to embellish or reinterpret the tonic of your piece so that we’re not just hearing the I chord over and over and over again.
Armed with this knowledge, we can extrapolate every other variation of changes that could be made between any two triads to determine whether that chord change is Journey movement or Home movement. This ultimately tells us how these chords function in our progression. The value of the newly created chord, major or minor, will tell us how the chord is going to make us feel.
Up until this point, we’ve only been dealing with major triads (hence all the roman numerals being upper case, prepare to see some crazy vi and ii7 shit coming up). By walking through all the variations of these two basic movements, I - V and I - IV, we will see all possible chord values and choices available in a progression.
Moving Only One Note!
If you believe it, the first two changes that we talked about, I - V and I - IV, are the only two options we have to change two of the notes in the first chord and have it result in a new chord that can still stack as a triad. This is again setting aside any chromatic notes, or mixture, or sus chords, or anything else that introduces something new to our tonic key.
If we instead choose to move one of the three original notes and leave the other two the same, we also only have two options:
B - E - G
C - E - A
Moving Two Notes
B - D - G
C - F - A
Moving Three Notes
D - F - A
B - D - F
I - iii
I - iii7
I - vii
I - vii7
I - viio
I - IV
I - ii
I - ii7
I - vi
I - vi7