Chord inversions are chords in which the root (1st degree) is no longer the bass note (the lowest note in the chord). This opens a new variety of sounds for any given chord.
Whenever chord notes are organized in their default order, we'll refer to this as the chord's root position.
Listen to how the 'C minor' chord sounds in its root position:
In a chord's 1st inversion, the chord's second note is the chord's bass note instead of the root. This can be achieved by lifting the root by an octave.
Listen to how 'C minor, 1st inversion' sounds:
Another way of naming inversions is by adding the new bass note to the original chord's name.
For example, a 'C minor 1st inversion' can also be called 'C minor over E' or 'Cm/E' in-short.
The 2nd inversion is achieved by lifting the bass note by an octave once again. This creates a chord where the original 3rd note is now the bass note.
Listen to how 'C minor over G' sounds:
If we were to go through this process of lifting the bass note by an octave once again, we'd find ourselves back with the chord's root position (all 3 notes of the chord have been lifted by an octave).
If the chord has 4 notes, there will be an additional 3rd inversions available. A 5 note chord will have a 4th inversion available, and so on.
Play Inversionist to get familiar and develop the ability to identify chord inversions by ear.