Harmony and Form

 

Harmony in western music is based on triads.  Triads are simple 3 note chords built on thirds.

triads

The chords above are written in root position, which is the most basic way to write a triad.  In root position, the root, which is the note that names the chord, is the lowest note. The third of the chord is written a third above the root and the fifth of the chord is written a fifth higher than the root which is a third higher than the third of the chord.  So the simplest way to write a triad is a stack af thirds above the root.

First and Second Inversions:  Any other chord that has the same named notes as a root position chord is considered to be the same chord but in a different position.  so all chords that have D natural, F sharp and A natural are considered to be a D major chord.  If the third of the chord is the lowest note than the chord is said to be in first inversion.  If the lowest note is the fifth of the chord it is in second inversion. 

inversions

It does not matter how far the higher notes are from the lowest note, or how many of each note there are at different octaves, all that matters is which note is lowest.