Adding color tones to a chord is like adding colors to a black and white drawing; it adds depth and dimension and well as bringing it to life.
There is a time and place, of course, for "black and white" music, just as there is in art. And many times as a musician I choose to use shades of grey to color my improvisations on the piano, just as an artist uses light and dark to create the feeling and mood of the sketch.
But there are also times when adding a splash of color can do wonders for your piano playing (or guitar or electronic keyboard or organ or whatever). These musical colors create nuances of texture and feeling that are just not available using shades of grey.
So what colors are available from your musical palate? And how do we blend them in to the existing framework of a song?
I'm glad you asked, because you will be astounded at the number of combinations or color tones that can be blended together into any given chord.
First, though, lets review what a basic black and white chord is made of. Every basic triad is composed of 3 notes: a root (the lowest note of the chord), a 3rd, and a 5th.
A major triad consists of a root, then the 3rd note of the major scale, then the 5th note of a major scale. For example in the key of C the major triad is C, E, and G. In the key of D the major triad is D, F#, and A. Why the F#? Because in the scale of D F# is the 3rd degree. So in the key of Db the major triad is Db, F, and Ab. Why the Ab? Because it is the 5th note in the scale of Db.
A minor triad consists of a root, a 3rd lowered one-half step, and a 5th of the major scale. So instead of E as the 3rd of the chord we use Eb. In the key of D, instead of F# being the 3rd we use F, since it is 1/2 step lower than F#.
An augmented triad consists of a root, a 3rd, and a 5th raised one-half step. So the C augmented triad would be C, E, and G#.
A diminished triad consists of a root, a 3rd lowered one-half step, and a 5th lowered one-half step. So the C diminished triad would be C, Eb, and Gb.
Those are the "black and white" chords: no color, but appropriate in most instances.
But when you want to add a flair of creativity to your playing, here is the color palate you have to work with:
*2nds: the 2nd note of a major scale.
*6ths: the 6th note of a major scale.
*major 7ths: the 7th note of a major scale.
*7ths: (also known as dominant 7ths): the lowered 7th of a major scale.
*9ths: the 9th note of the major scale (same as the 2nd note except an octave higher). If you're wondering why the 9th is not just called the 2nd, it's because the 9th is combined with other color tones, whereas the 2nd is not.
*Flat 9ths: the 9th note of a major scale lowered one-half step.
*11ths: the 11th note of a major scale (same as the 4th except an octave higher).
*Sharp 11th: the 11th note of a major scale raised one-half step.
*13th: the 13th note of a major scale (same as the 6th, except an octave higher).
So you can add a 6th to a major or minor triad to create a brighter sound. You can add a major 7th to a major or minor or diminished triad to create another kind of sound. You can add a 7th (dominant 7th) to a major, minor, diminished, or augmented chord to create another kind of sound. Or you can add a 7th along with a 6th; or a 9th along with a major 7th; or a 9th along with a 7th; or an 11th along with a 9th and a 7th; or a 13th along with an 11th and a 9th and a 7th.
And on and on. We could go on combining color tones until the cows come home, but the best way for you to learn what's possible is to just dig in and experiment. You'll find many, many exciting combinations you can use in various musical situations that will brighten your song and add a rainbow of colors to your creative improvisations.