What is a Chord?
First thing we must understand are the intervals that make up a Major Scale
R – W – W – H – W – W – W –H – R
For the scale of C this would be C D E F G A B C we can also number these notes 1 2 3 4 5 6 7 8
Two Whole Tones together are known as a major 3rd
A Whole tone and a Half one are known as a minor 3rd
These are the key interval that we need to know when playing a chord
General definition of a chord
A chord is the layering of several tones played simultaneously - usually built on superposed thirds. Chords are defined by their root note and their quality (major, minor, 7, etc) - and eventually by their inversion.
A triad is a chord made of three notes. It consists of a root and the third and fifth above it. The most common triads are:
Major - has a
major third and a perfect fifth
Minor - has a minor third and a perfect fifth
Diminished - has a minor third and a diminished fifth
Augmented - has a major third and an augmented fifth
After you've figured out which notes can be in a chord, those notes can actually come from any octave. They don't have to be played in scale order! In other words, the root note does not have to be played in the root position. This is called inversion.
Furthermore, each note in the chord does not have to be played only once! That's right, if you had enough fingers, and played every C on the piano, yet played only one E and one G at the same time, you'd still have a C major chord. The nearly infinite variety of chord combinations is what colors the music and gives it depth.