A knowledge of chord progressions will help you communicate and play with other musicians. Knowing the most commonly used chord progressions allows for greater enjoyment and unity when playing with other musicians.
The most common chord progression is I-IV-V. Note that Roman Numerals are used to describe these chord progressions. Many songs use only these three chords. If one views chords as a set of balancing scales with the root note and octave root at opposing ends it will be noted that the IV and V chords are at equal distance respectively to the root and octave root. Take for example the key of C major:
C - D - E - F - G - A - B - C
You will see that the G note (or chord) is a fifth above the root note. The note F is a fifth below the octave. This movement of a fifth is very pleasing to the human ear in its sense of balance and cohesion in relation to the root note. Another way to view chord progressions is that of a journey. In the sense that the root (or tonic) chord is the starting point and the octave root is at the end. All other points (chords) provide interest and variation with the fourth and the fifth chord occupying a special place on the journey due to them being half-way.
Many chord progressions start at the tonic (I), moves away to somewhere else, only to come back to the tonic. You can play this progression with major chords or you can substitute minor chords for the IV or V.
Applying the I-IV-V
Eddie Cochran and Buddy Holly are two artists who have used this progression extensively. Note that this chord progression uses a V7 chord. A V7 chord is just a V chord with an extra note. It is so common a device that when learning a chord progression many guitarist will play it through a few times using I-IV-V (normal V chord with no extra note) and then will play the chord progression I-IV-V7 a few times before switching back to the normal I-IV-V.
This progression is commonly referred to as the 50's progression, because it was common to many of the popular songs of the 1950's, notably "Stand by Me". Here is the progression in the key of G major.
This is a popular progression at the beginning of a much larger line, and can be combined with many other scale degrees.
As its name indicates, the progression is: ii-min7, V7 and Imaj7.
Alternatively you can change the chord type on the II, and alter the voicing of the V. Some examples are:
- ii-m7b5(9) V7alt Imaj7
Applying the ii-V-I
ii-V-Is can be chained together, creating complex progressions. Here's an example:
C Bm7b5 E7 (I ii V) Am7 Dm7 G7 (I ii V) C (etc...) (I etc..)
An example of complicated progression that can be created this way is the "Coltrane Changes", where the "I" chords move by Major 3rd intervals. Here's a simple example:
Dm7 G7 Cmaj7 (ii V I ) F#m7 B7 Emaj7 (ii V I ) Bbm7 Eb7 Abmaj7 (ii V I ) Dm7 etc... (I etc...)
The way the ii-V-I progression works is first that it moves by 4ths upwards, which very often produces interesting results, and the 7th goes down a half tone below and becomes the following chord's 3rd.
The Minor ii-V-i
Another commonly used chord progression is the minor ii-V-i. One can derive this from the melodic minor scales shown above, while substituting a IminMaj7 for the IMaj7 chord, or by using three modes from one harmonic minor scale , which produces the following chord progression: